NFC Glossary

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213 / 215 / 216 MEMORY VARIANTS

The core baseline capacity tiers of the NTAG21x family, offering 144 bytes, 504 bytes, and 888 bytes of usable NDEF memory respectively, all built on identical Type 2 protocol logic. Detailed chip pages: NTAG213, NTAG215 and NTAG216.

3K3DES / 2K3DES

The legacy Triple-DES cryptographic modes supported by MIFARE DESFire chips using two (112-bit) or three (168-bit) secret keys to authenticate and encrypt data frames, kept primarily for backward compatibility with older transit infrastructures.

8-BIT CHARACTER ENCODING (NDEF)

The structural byte arrangement used within NDEF Text Records to encode characters, typically relying on UTF-8 or UTF-16 protocols declared in the payload status byte.

AAR (ANDROID APPLICATION RECORD)

A special NDEF record that asks an Android device to open a specific application when the tag is read, or its download page if the app is absent. Android-specific, it is ignored by iPhones: a tag intended for every audience should never rely on it alone.

AAR OVERRIDE

A phenomenon where an Android device ignores the primary NDEF record (such as a web link) and opens directly the app specified in the Android Application Record, preventing standard web redirection unless the application in question is uninstalled.

ABORT TRANSACTION

An explicit security command in MIFARE DESFire that cancels an ongoing file update session, immediately rolling back any uncommitted data modifications to preserve memory integrity.

ACK / NAK (NFC DIALOGUE)

The fundamental positive (Acknowledgement) and negative (Negative Acknowledgement) control signals exchanged at the protocol level between reader and tag to validate command reception.

ACTIVE ATTACK

A cyber-security intrusion vector where an adversary actively injects, alters, or suppresses radio frames during a live NFC communication session rather than passively listening.

ACTIVE LOAD MODULATION (ALM)

An advanced card emulation technique where a small device actively drives an RF signal in burst bursts back to the reader rather than passively modulating the field, compensating for extremely tiny antennas in wearables.

ACTIVE VS. PASSIVE MODE

The two primary operational modes of NFC radio communication. In active mode, both devices generate their own RF field to transmit data (common in device-to-device exchanges). In passive mode, only the initiator (the reader) generates the field, while the target (the tag) powers itself off that field and replies via load modulation.

AES-128 AUTHENTICATION

The mutual challenge-response authentication protocol built on 128-bit AES secret keys, by which secure NFC chips (MIFARE DESFire, ICODE DNA, NTAG 424 DNA) and a reader prove knowledge of the shared key and derive session keys before any protected memory access.

AES (ADVANCED ENCRYPTION STANDARD)

A symmetric cryptographic algorithm integrated into high-security NFC chips (such as MIFARE DESFire or NTAG 424 DNA) to ensure data confidentiality, mutual authentication, and anti-cloning protection. Unlike basic memory tags readable in the clear, AES-enabled tags interact securely with readers using secret keys.

AFI (APPLICATION FAMILY IDENTIFIER)

A specific configuration byte used primarily in ISO/IEC 15693 (Type 5) chips that categorizes the tag's application domain (e.g., medical, library, industrial logistics). It allows a reader to quickly filter and target only tags belonging to a specific family without reading their entire memory content.

AIR INTERFACE

The physical medium (specifically the 13.56 MHz alternating magnetic field) and the associated radio modulation rules that govern wireless transmission between a reader and a tag.

AMPLITUDE MODULATION (ASK)

The process by which the reader transmits its commands to the tag, by varying the amplitude of the carrier according to an agreed code. It is the downlink direction of the dialogue, of which load modulation is the uplink counterpart.

ANDROID BEAM

A former Android feature exploiting peer-to-peer mode to exchange content between two phones placed back to back, since removed from the system. Its name still surfaces in dated documentation; its disappearance illustrates the refocusing of consumer NFC on tags and payment.

ANTENNA

A spiral of conductive material, most often copper or aluminum, surrounding the chip of a tag. It captures energy from the reader's magnetic field and serves as the communication channel in both directions. Its accidental severing, by a fold or a cut, leaves the tag permanently mute: it is the fragile point of the object.

ANTENNA MANUFACTURING

Tag antennas arise from three main processes: the etching of an aluminum or copper sheet, the printing of conductive inks, and the winding of copper wire, reserved for thick formats such as tokens and rigid cards. The process influences fineness, cost and performance; the user need not choose it, but the vocabulary appears in manufacturers' sheets.

ANTENNA TUNING

The adjustment of a tag's or reader's antenna so that it resonates precisely at the working frequency, the condition for efficient energy transfer. Careful tuning, a matter of design and manufacturing, explains why two tags of equal size can offer noticeably different reading distances.

ANTI-COLLISION

A mechanism provided by the standards to handle the simultaneous presence of several tags in a reader's field, by identifying them one at a time. It explains why a reader can untangle a confused situation, not why it should be made comfortable: in practice, presenting tags one by one remains the golden rule of reliability.

ANTI-METAL TAG

A tag incorporating a ferrite layer that shields it from metal surfaces, which would otherwise smother all communication. Indispensable whenever a tag must live on or near metal, it is the cure for that great classic, the silent tag on a steel door. Also sold under the name on-metal tag.

ANTI-PASSBACK

A security enforcement rule used in access control systems preventing a credential (or cloned tag) from being scanned twice in succession to gain entry without an intervening exit scan.

ANTI-REPLAY PROTOCOL

A cryptographic architecture ensuring that captured radio transmission frames cannot be recorded and played back by an unauthorized party to execute valid commands.

ANTI-TEARING

A protection built into certain chips against interrupted writes, tag pulled from the field too soon: sensitive data, counters or lock bits, are updated in a way that stays consistent even if the exchange is cut. It does not excuse the gesture: holding the tag still until confirmation remains the rule.

APDU (APPLICATION PROTOCOL DATA UNIT)

The elementary unit of dialogue between a reader and a smart card, defined by the ISO/IEC 7816 standard: one command sent, one response received. APDUs are the low-level language of advanced cards, banking or identity; the everyday NFC user never touches them, applications handling them on their behalf.

APPLICATION ID (AID)

A unique binary identifier (typically 5 to 16 bytes) used in ISO/IEC 7816-4 protocols to select a specific application hosted inside a multi-application secure element or smart card.

APPLICATION ID (AID - DESFIRE)

A 3-byte unique location identifier within a DESFire chip used to address a specific application (e.g., Transit = 0x000001, Access Control = 0x000002) within its multi-application file system.

APPLICATION MASTER KEY (AMK)

The administrative key assigned to an individual DESFire application, granting rights to modify access keys, create/delete files, or change application settings without needing the card-level master key.

ASK 10% / ASK 100%

The two degrees of amplitude modulation depth specified in radio protocols like ISO/IEC 14443. ASK 100% (used in Type A) completely cuts off carrier power for fractions of a microsecond to transmit bits, whereas ASK 10% (used in Type B) merely dips the amplitude, allowing continuous power transfer to high-consumption dynamic cards.

ASYMMETRIC CRYPTOGRAPHY (ECC/RSA)

Public-key cryptographic schemes supported by high-end smart cards enabling digital signatures and key exchanges without sharing secret master keys between devices.

ATQA (ANSWER TO REQUEST, TYPE A)

The first response a Type A chip addresses to the reader interrogating it, in the form of a code announcing some of its characteristics. Together with the SAK, the ATQA contributes to the technical identification of the chip as the dialogue is established; these values appear in advanced reading applications and serve mainly for diagnostics.

ATS (ANSWER TO SELECT)

The specific response frame sent by an ISO/IEC 14443 Type A chip to the reader upon receiving a Select command, detailing its low-level communication parameters, such as maximum frame size and timing requirements, before initiating higher-layer protocols.

ATTACK SURFACE (NFC)

The sum total of physical, radio, and software vulnerabilities exposed by an NFC system, ranging from physical chip probing to application-level URL spoofing.

ATTENUATION

The loss of radio-frequency signal strength caused by obstacles, distance, or absorbing materials in the environment. In NFC, excessive attenuation from metallic enclosures or dense liquids can drop the RF energy below the threshold needed to power passive chips.

AUTH0 / ACCESS REGISTERS

Configuration bytes in NTAG21x chips determining the starting memory page address from which password protection is enforced, allowing flexible split configuration between public and private memory zones.

AUTHENTICATION MAC

A cryptographic Message Authentication Code appended to NDEF records that allows a server to verify that the tag data was generated by an authorized entity.

AUTHLIM (AUTHENTICATION LIMIT)

A hardware security setting in NTAG21x chips specifying the maximum number of consecutive failed password attempts permitted before the chip permanently locks itself against further attempts.

BACKGROUND TAG READING

The behavior of recent iPhones, which detect tags with no application open, screen on, and offer the corresponding action through a notification. It requires properly encoded NDEF content, triggers only one action per tag, and has its exceptions, device locked in some cases, chip busy with a payment.

BACKUP DATA FILE

A specific DESFire file type featuring two identical internal memory banks; updates are written to a secondary staging buffer and swapped only upon executing a Commit Transaction command.

BANDWIDTH (13.56 MHZ)

The frequency range centered around 13.56 MHz (typically $\pm 7$ kHz to $\pm 848$ kHz depending on subcarriers) occupied by modulated data transmission.

BATTERY ASSISTED LOAD MODULATION

A technology in active devices where an onboard battery boosts the load modulation response back to the reader, enabling tiny antennas to act like full-sized credit cards.

BATTERY-ASSISTED PASSIVE (BAP)

A hybrid tag architecture featuring an internal battery used exclusively to power integrated sensors or onboard microprocessors, while still relying entirely on the reader's RF field for data transmission via load modulation.

BIT-ORIENTED ANTI-COLLISION

The precise low-level mechanism used in ISO/IEC 14443 Type A where a reader detects bit collisions in real time during tag identification, allowing it to isolate and talk to one chip even when several share the field.

BIT RATE ADAPTATION

The dynamic adjustment of data transmission speeds (e.g., from 106 kbps up to 424 kbps or 848 kbps) negotiated between a card and a reader based on field quality.

BLOCK WRITE COMMAND

An instruction enabling a reader to overwrite an entire memory page or block in a single programming cycle, speeding up bulk encoding workflows.

BLUETOOTH

A medium-range wireless technology relying on two active, powered devices, designed for continuous connections, audio or data. It does not compete with NFC; it complements it: to NFC the instant introduction, to Bluetooth the lasting conversation.

BPSK (BINARY PHASE SHIFT KEYING)

A digital modulation method where the phase of the carrier signal is shifted to represent binary data. It is commonly used in ISO/IEC 14443 Type B communications to ensure robust uplink signal transmission from the card to the reader.

See also: ISO/IEC 14443, NFC-B, load modulation.

BYTE

The unit of memory measurement, corresponding in practice to roughly one character of text within a record. With tag capacities counted in hundreds of bytes, the byte is the currency in which every encoding project is budgeted.

CAPABILITY CONTAINER (CC)

A small block of information sitting at the head of some tags' memory, describing their characteristics to the reader, version, size, access rights, before any content is read. An expert-mode notion, visible in raw reads, that applications interpret on your behalf.

CARD EMULATION

One of NFC's operating modes, in which a device passes itself off as a contactless card to a terminal: this is how a phone pays in place of a bank card. On Android, a software form of this mode is open to applications; on iPhone, emulation remains essentially reserved for system services.

CARD IDENTIFIER (CID)

A dynamic address allocated by a reader during an active multi-tag or multi-card dialogue session, enabling it to maintain concurrent logical channels with several contactless cards simultaneously.

CARRIER (13.56 MHZ)

The base wave of the NFC dialogue, emitted by the reader at the single frequency of 13.56 megahertz, onto which the exchanged information is imprinted. The tag never produces its own: it modulates the reader's.

CASCADE TAG (CASCADE BYTE)

A special marker byte (0x88) returned during anti-collision that alerts the reader that the tag's UID exceeds 4 bytes and requires an additional cascade cycle.

CFG_LOCKED BIT

A permanent protection bit in NTAG registers that freezes all configuration pages, preventing unauthorized modifications to passwords, mirror settings, or lock configurations.

CHAINING (NDEF / APDU)

A technique used when data exceeds maximum single-frame limits, splitting large payloads into sequential linked packets reassembled at the receiving end.

CHANGE KEY COMMAND

A protected DESFire instruction that allows an authenticated user to overwrite a specific access key stored in an application with a new key value.

CHIP

The miniature integrated circuit at the heart of the tag, housing the memory, the dialogue logic and the protection functions. Its commercial reference determines the tag's capacity and possibilities; its size, under a square millimeter, explains why a tag fits inside a sticker.

CIPHER MESSAGING (ICODE)

An operational mode on cryptographic ICODE chips where read and write payloads are fully encrypted over the air using symmetric AES algorithms to protect data privacy in logistics chains.

CIPURSE

An open, standards-based security scheme defined by the OSPT Alliance for transit ticketing and access control, designed as an open-source alternative to proprietary smart card encryption technologies.

CLEAR TEXT TRANSMISSION

The transmission of unencrypted, plain data across the radio link, readable by any listening device within physical eavesdropping range.

CLONING

The reproduction of an NFC medium. On standard tags, only the content can be copied: the chip's unique identifier, engraved at the factory, cannot be reproduced, which protects systems built on that identity. Let the legal obvious be stated: duplicating your own tags is normal use; reproducing other people's media, badges or service cards, is illegal.

CMAC (CIPHER-BASED MESSAGE AUTHENTICATION CODE)

A cryptographic checksum generated during DESFire AES communication sessions and appended to data frames to guarantee that transferred data has not been altered or injected by an attacker.

COMMIT TRANSACTION

The instruction that finalizes all pending updates across Backup Data Files, Value Files, or Record Files within a DESFire transaction, executing all memory writes atomically.

CONFIGURATION PAGES (NTAG)

Dedicated memory pages located at the tail end of an NTAG's EEPROM address space that house system settings, password hashes, mirror pointers, and access rules.

CONTACTLESS

The generic qualifier for technologies that work by simple approach, without insertion or plugging in, of which NFC is today the most everyday representative. In common parlance, the term also covers payment by card or phone.

CONTACTLESS PAYMENT

NFC's most widespread application, in which a card or phone dialogues with a terminal in emulation mode, under the protection of dedicated banking components and protocols. Its mere presence on a phone attests that the phone has NFC.

CORE NFC

The name of the software framework through which Apple gives iPhone applications access to the NFC chip. It allows the reading and writing of common tags as well as certain advanced commands, but within a stricter perimeter than Android's: operations initiated by the user through a system scan sheet, card emulation reserved for the system, low-level functions under supervision. These limits explain the differences between the Android and iOS versions of NFC applications.

COUNTER (ICODE READ/WRITE)

An integrated hardware counter present on modern ICODE chips that automatically increments upon every successful read or update operation, ideal for usage tracking or tamper verification.

COUPLING

The degree of magnetic linkage between the reader's antenna and the tag's, on which the amount of transferred energy directly depends. It grows with proximity, alignment and the tuning of the two antennas: the right gesture, tag presented squarely against the reading zone, is nothing other than the search for the best coupling.

CRC (CYCLIC REDUNDANCY CHECK)

An error-detection mechanism accompanying the exchanges between reader and tag: a checksum attached to the frames allows corrupted transmissions to be rejected. It works in silence and contributes to the reliability of the dialogue despite the brevity of the contact.

CRYPTOGRAPHIC NONCE

A single-use random number generated during an authentication session to ensure each cryptographic response is unique and immune to replay attacks.

CUSTOM COMMAND SET (NXP ICODE)

A suite of proprietary commands extending standard ISO/IEC 15693 features, providing high-speed inventory reading, custom memory management, and advanced security flags on ICODE chips.

CYCLIC RECORD FILE

A DESFire file structure designed for transaction logging, where write operations append new records sequentially until the file is full, automatically overwriting the oldest record.

DATA RATE

The transfer speed of NFC exchanges, on the order of one hundred and six kilobits per second in the usual case, more in certain variants. Modest by the standards of modern networks, this rate is of no practical consequence: tag contents are counted in hundreds of bytes and travel in a fraction of a second.

DATA RETENTION

The length of time a chip's memory keeps its content without any power, guaranteed by manufacturers for a decade at minimum and generally far longer in practice. Together with write endurance, it makes tags objects built for a lifetime of use.

DEEP LINK

An address which, instead of a web page, directly opens an application or a specific screen within it. Encoded in a tag, it makes the gesture more direct for whoever owns the app; its fragility, behavior varying across platforms and versions, argues for preferring a classic web link, capable of redirecting to the app.

DEFAULT ACCESS PASSWORD

The factory-set 32-bit password state (typically 0xFFFFFFFF) present on unconfigured NTAG chips before custom password protection is activated by the user.

DELEGATED APPLICATION MANAGEMENT

A feature in MIFARE DESFire EV2/EV3 allowing third-party application providers to securely load, update, or remove their own applications on a multi-use card using pre-loaded cryptographic tokens, without sharing master keys.

DES (DATA ENCRYPTION STANDARD) / 3DES

A legacy symmetric encryption algorithm historically used in smart cards, now largely superseded by AES due to security vulnerabilities.

DESFIRE NATIVE COMMANDS

The proprietary instruction set used by NXP DESFire chips (e.g., Select Application, AuthenticateAES, ReadData), which can be transmitted directly or wrapped inside standard ISO/IEC 7816-4 APDUs.

DESTROY COMMAND (ICODE)

An irreversible, password-protected hardware command that permanently disables the ICODE chip's RF interface, rendering the label completely mute forever.

DUAL-FREQ HYBRID TAG

A single tag housing two distinct chips and antennas operating at different frequencies (e.g., 13.56 MHz NFC and 860–960 MHz UHF RFID) for multi-use logistics.

DUAL-INTERFACE CHIP (DYNAMIC TAG CHIP)

A specialized chip equipped with both a wireless NFC interface and a wired bus interface (such as I2C or SPI). It enables an external microcontroller (inside an electronic device or appliance) to update the tag's NDEF memory directly, turning the tag into a dynamic bridge between a smartphone and embedded electronics.

See also: I2C / SPI, field detect pin, NDEF.

DUAL MODE CARD

A card capable of operating both as a contact smart card (via ISO/IEC 7816 metallic contacts) and a contactless card (via 13.56 MHz NFC).

DYNAMIC LOCK BITS

A set of secondary memory lock indicators present on certain Type 2 or Type 5 chips that allow users to permanently freeze high-address memory blocks independently from the baseline capability container lock bits.

DYNAMIC NDEF

A mechanism where the content returned in an NDEF message is calculated on the fly by an embedded microcontroller or an advanced chip function at the precise moment of reading, rather than being statically saved in EEPROM memory. This enables dynamic values like live sensor readings or fresh cryptographic tokens.

DYNAMIC TAG

A commercial expression describing a tag whose content appears to be modifiable remotely. Lucidity is in order: the tag itself is always static; it is the redirect it contains which, pointing to an editable destination, creates the dynamic effect. Understanding this mechanism saves you from paying for a mystery.

EAS (ELECTRONIC ARTICLE SURVEILLANCE)

A dedicated 1-bit status flag embedded in ICODE chips (notably ICODE SLIX) used by retail and library systems to trigger theft-prevention alarms at exits when items are moved without being checked out.

EAS LOCK

An administrative status bit that freezes the state of the EAS flag, preventing unauthorized modification of the theft-prevention status by unauthenticated readers.

EAVESDROPPING

The remote interception of a contactless exchange by an equipped third party, without taking part in the dialogue. The physics of the near field makes it difficult, the signal collapsing at short distance, but not theoretically impossible: transactional systems answer it by encrypting their exchanges, while the plain content tag, readable by all, has by definition nothing to hide.

ECMA-340

The reference under which NFC's founding standard was also published, twin of ISO/IEC 18092. Coming across it in documentation should not confuse: it is the same text under two banners.

EEPROM

The type of memory fitted to common NFC chips: electrically rewritable and non-volatile, meaning it retains its data without any power supply. It is what allows a tag to keep its content for years on end, with no battery and no maintenance.

ELECTROMAGNETIC COMPATIBILITY (EMC)

The ability of an NFC device to operate correctly in its radio environment without causing or suffering intolerable electromagnetic interference.

ELECTROMAGNETIC INDUCTION

The physical phenomenon by which a varying magnetic field gives rise to a current in a conductive loop. It is what powers tags: the tag's antenna, crossed by the phone's field, produces the current that wakes the chip. NFC's entire battery-free architecture rests on this principle.

EMV

The set of specifications governing card payment, whose contactless side rests on the NFC layer. It is what governs the dialogue between your card or phone and the terminal, well above the mere radio transport.

ENCAPSULATION

The protective enrobing of the inlay in its final carrier, plastic lamination, epoxy resin or mass casting depending on the product. It is what decides the tag's resistance to water, shocks and cleaning products, and therefore its fitness for outdoor life.

ENCODING

The established term for writing content into a tag: to encode a tag is to burn one's records into it. Encoding entirely replaces the previous content and can be performed freely as long as the tag is not locked.

ENCRYPTION

An important point of lucidity: the NDEF records of a standard tag are not encrypted. Any phone that reads the tag reads its content in the clear; a tag's confidentiality rests on its physical location, never on a cryptographic secret. Cryptographic functions do exist, but on specialized chips serving other purposes, access control or product authentication.

ENERGY HARVESTING

The ability of certain chips to draw a surplus of energy from the reader's field to power an external component, most often a light-emitting diode. It is the principle behind tags that blink when read: an elegant curiosity that illustrates the strictly passive nature of the technology.

ESD PROTECTION (ELECTROSTATIC DISCHARGE)

Internal protection diodes built into NFC chips to absorb high-voltage static discharges from human touch without destroying internal circuits.

EV1 / EV2 / EV3 GENERATIONS

Sequential architecture release generations of NXP's MIFARE chip families, reflecting steady additions of modern encryption features and memory enhancements. Detailed chip pages: MIFARE DESFire EV1, EV2 and EV3.

EXECUTION ENVIRONMENT (EE)

The secure execution space within a smartphone operating system or secure element where sensitive payment or access control applications run safely.

EXPRESS MODE

An iPhone function granting certain transit or access cards privileged handling: validation with no unlocking or authentication, and continued operation for a while on reserve energy after the battery dies. It illustrates the deep integration of NFC into the phone's hardware, well beyond the mere reading of tags.

EXTENDED LENGTH APDU

A variant of the standard APDU frame allowing command payloads larger than 256 bytes (up to 65,535 bytes) to be transmitted in a single exchange, accelerating data transfers on high-capacity Type 4 smart cards like identity documents or passports.

FAR FIELD

The zone far from an antenna where energy propagates as radiated waves, the territory of Wi-Fi, Bluetooth and radio. NFC deliberately turns its back on it to inhabit the near field: the boundary between the two explains the gulf in range that separates these technologies.

FARADAY CAGE SLEEVE

A conductive metal-lined pouch or wallet slot that completely blocks 13.56 MHz radio waves, protecting contactless cards from unwanted scanning or skimming.

FAST_READ (NTAG COMMAND)

An optimized NTAG custom instruction allowing a reader to fetch large blocks of consecutive memory pages in a single command cycle, bypassing the standard 4-page read limit.

FAST READ SLIX

An optimized operational command that doubles the standard data rate during continuous block reads, drastically reducing scan times on high-speed conveyor belts or sorting lines.

FELICA

A contactless card technology of Japanese origin, integrated into the NFC universe under the name NFC-F and corresponding to NFC Forum Type 3. Ubiquitous in East Asian transport and payments, it remains marginal in Europe; smartphones largely support it for reading. Detailed chip pages: FeliCa Lite-S RC-S966 and FeliCa Lite RC-965.

FERRITE CORE ANTENNA

An antenna design where the conductive wire loop is wrapped around a compact ferrite cylinder rather than laid flat on a planar film, creating a highly directional magnetic field suited for micro-tags and specialized industrial tools.

FERRITE LAYER

A sheet of magnetic material inserted between a tag and a metal surface to channel the field and preserve communication. It is what makes anti-metal tags and metal NFC cards possible, bare metal otherwise smothering any dialogue.

FIELD DETECT PIN

A dedicated hardware output pin on dynamic NFC chips that signals an external host microcontroller whenever an active 13.56 MHz RF field is detected. This allows the host device to sleep in a low-power state and wake up instantly the moment a user taps their phone against the NFC antenna.

FILE SELECTION APDU

An ISO/IEC 7816-4 command sent to select a specific data file or directory within a smart card's hierarchical file system.

FIRMWARE UPDATE OVER NFC

The process of transmitting new operational software to an embedded microcontroller in an electronic device using high-speed NFC dynamic tag chips.

FLIPPER ZERO

A small multi-protocol device intended for radio-frequency enthusiasts, capable among other things of reading and emulating various contactless media. A legitimate learning tool on one's own equipment, it is subject to the same legal framework as any tool of its kind: using it on other people's systems, without authorization, is illegal. This blog devotes guides to it, always accompanied by this reminder.

FRAM MEMORY (ICODE)

Ferroelectric Random Access Memory used in specialized ICODE variants to offer ultra-fast write speeds and near-infinite write endurance compared to traditional EEPROM.

FRAME WAITING TIME (FWT)

The maximum time limit defined in ISO protocols that a reader will wait for a card to begin sending its response before declaring a timeout error.

FREE MEMORY

A system command in DESFire returning the exact amount of remaining, unallocated EEPROM storage available for creating new applications or expanding existing files.

FREQUENCY (13.56 MHZ)

NFC's single working frequency, identical for every device and tag in the world, inherited from the high-frequency branch of RFID. This universality is one of the keys to the technology's interoperability.

FSK (FREQUENCY SHIFT KEYING)

A digital modulation scheme where data bits are represented by subtle shifts between two distinct subcarrier frequencies. While standard NFC (ISO/IEC 14443 Type A/B) uses ASK and BPSK, FSK is occasionally encountered in specialized legacy vicinity tags or hybrid industrial RFID transponders.

FULL DUPLEX VS. HALF DUPLEX

NFC operates strictly in half-duplex mode: devices alternate between transmitting and receiving, rather than sending and receiving simultaneously.

GLASS TRANSPONDER (AMPOULE)

A miniature tag encapsulated inside a hermetically sealed glass tube, historically used for animal identification and harsh chemical exposure.

GUARD TIME

The minimum pause required between consecutive command transmissions in the NFC radio dialogue, ensuring that passive tags have sufficient time to reset their internal processing states between operations.

HANDOVER (CONNECTION HANDOVER)

An NFC Forum specification organizing the passing of the baton between NFC and another wireless technology: the NFC touch exchanges the connection parameters, then Bluetooth or Wi-Fi take over. It is the standardized mechanism behind pairing by a simple touch.

HARDWARE EXCEPTION SENSORS

Miniature micro-sensors embedded directly onto the silicon wafer of DESFire chips to detect physical attack attempts, such as light probing, extreme voltage fluctuations, or unnatural clock frequencies, instantly zeroing sensitive RAM.

HCE (HOST CARD EMULATION)

The software variant of card emulation, specific to Android, in which the system rather than a dedicated secure component plays the role of the card, with no SIM or embedded secure element required.

HCI (HOST CONTROLLER INTERFACE)

A logical interface defined by the NFC Forum that standardizes communication between an NFC controller chip and the main execution environment or Secure Element of a device. It operates behind the scenes in smartphones to coordinate reader, card emulation, and peer-to-peer functions.

See also: secure element, card emulation.

HEXADECIMAL

Base-sixteen notation, mixing digits and the letters A to F, used to represent the binary data of chips: unique identifiers, raw contents, technical values. Coming across hexadecimal in a reading application is normal and holds no mystery: it is a notation, not a secret code.

HF (HIGH FREQUENCY)

The radio frequency range spanning from 3 MHz to 30 MHz. NFC operates specifically at 13.56 MHz within this band. HF technologies differ fundamentally from LF (Low Frequency, 125–134 kHz) used in legacy badges and UHF (Ultra High Frequency, 860–960 MHz) used in long-range supply chain RFID.

HIGH-DENSITY INVENTORY (HD INVENTORY)

An advanced anti-collision technique utilized by ICODE readers to systematically isolate and inventory thousands of tightly packed vicinity labels (e.g., stacked books or pharmaceutical bottles) per minute.

I2C HOST BRIDGE (NTAG 5)

A physical dynamic interface built into NTAG 5 series chips that links a smartphone's NFC connection directly to an external host microcontroller via a wired I2C bus.

I2C MASTER EXTENSION

A feature of advanced dynamic tags allowing the chip to initiate communication over an I2C bus as a master rather than acting solely as a passive slave device.

I2C SLAVE ADDRESS (NTAG)

The configurable bus address used by a dynamic NTAG chip to identify itself when communicating with onboard electronics on a printed circuit board.

I2C / SPI (INTERFACE)

Standard wired serial protocols used by embedded microcontrollers. In the NFC context, dynamic chips use I2C or SPI to allow host hardware to communicate directly with the NFC chip's internal memory without radio communication.

ICODE

A chip family falling under the ISO/IEC 15693 standard, hence the NFC-V world and Type 5, widespread in industrial labeling, libraries and logistics. Smartphones can read it, but its natural home remains professional chains. All chip pages of the family are listed in the NFC chips knowledge base.

ICODE DNA

The high-security flagship chip in the ICODE product line, featuring AES-128 cryptographic authentication, dynamic cryptographic URLs, and high-durability memory for anti-counterfeiting. See the full ICODE DNA chip page.

ICODE SLI / SLIX / SLIX2

The foundational generations of NXP's vicinity memory tags conforming to ISO/IEC 15693 (Type 5), offering varying memory capacities (from 1024 to 2560 bits), extended data retention, and enhanced privacy modes. Detailed chip pages: ICODE SLI, ICODE SLIX and ICODE SLIX2.

IN-FIELD ENERGY HARVESTING (NTAG 5)

The ability of advanced NTAG chips to convert the reader's 13.56 MHz magnetic field into regulated DC power (a regulated 1.8 to 3.3 V rail, up to several milliwatts) to feed external sensors or microcontrollers without batteries.

INDUCTIVE COUPLING

The core physical coupling mechanism of NFC, where a primary reader coil and a secondary tag coil form an air-core transformer, transferring power and data across short distances through a shared magnetic field.

INGRESS PROTECTION RATING (IP)

A standardized two-digit rating qualifying a product's sealing against dust and water. On a tag meant for the outdoors or for washing, it is the mention to look for in the product sheet, the chip fearing nothing but its carrier and its encapsulation making all the difference.

INITIALIZATION VECTOR (IV)

A random or pseudo-random binary sequence used alongside secret AES keys in encrypted tags (such as NTAG 424 DNA or MIFARE DESFire) to ensure that two identical operations never yield the same encrypted output.

INLAY

The assembly formed by the chip and its antenna mounted on a carrier film, prior to integration into the final product, sticker, card or object. It is the component manufacturers insert into media; its quality determines the reliability of the finished tag.

INTELLIGENT FIELD MANAGEMENT

A power-saving feature in modern smartphones where the NFC controller continuously pulses tiny probing bursts of RF energy to check for tag presence, spinning up to full power only when a passive antenna enters the field.

A feature introduced in MIFARE DESFire EV2 allowing specified applications to grant read-only or read/write file access to other independent applications hosted on the same chip.

INTERFACE ARBITRATION

The hardware logic that prevents collisions when a smartphone RF scan and a host microcontroller attempt to read a dynamic tag's memory at the same moment.

INTEROPERABILITY

The ability of tags and readers from all manufacturers to work together, guaranteed by compliance with ISO standards and NFC Forum specifications. It is what makes NFC's founding promise possible: any compliant tag, read by any smartphone.

INVENTORY COMMAND (ISO 15693)

The core anti-collision request sent by a reader to query all ICODE tags within range, retrieving their 64-bit UIDs sequentially.

INVENTORY READ COMMAND

A hybrid ICODE command combining inventory anti-collision with data reading, allowing a reader to fetch identification numbers and memory contents simultaneously in one operational step. A Fast Inventory Read variant performs the same operation at double data rate.

ISM BAND

A portion of the radio spectrum reserved for industrial, scientific and medical uses, usable without a license within the emission rules. NFC's frequency sits within it: it is this status that lets billions of devices dialogue legally everywhere in the world.

ISO-DEP

The transport protocol defined by the fourth part of the ISO/IEC 14443 standard, by which advanced cards, banking ones in particular, and Type 4 tags dialogue. Its name appears in the technical sheets of advanced reads; it signals a chip speaking the language of smart cards rather than that of simple memory tags.

ISO/IEC 14443

The standard for proximity contactless cards, NFC's main technical foundation, declined in two dialogue variants, Type A and Type B. The vast majority of consumer tags fall under it, on the Type A side.

ISO/IEC 14443-1 (PHYSICAL CHARACTERISTICS)

The specific part of the proximity standard defining physical dimensions, thermal limits, surface pressure, and mechanical bending tolerances.

ISO/IEC 14443-2 (RF POWER AND SIGNAL INTERFACE)

The standard section governing carrier frequency, power levels, modulation depths, and bit coding formats for Type A and Type B communications.

ISO/IEC 14443-3 (INITIALIZATION AND ANTI-COLLISION)

The standard section detailing the exact command sequences, frame structures, and bit-level anti-collision rules required to select individual cards.

ISO/IEC 14443-4 (TRANSMISSION PROTOCOL)

The standard section establishing high-level half-duplex block transmission protocols, framing options, and error recovery algorithms.

ISO/IEC 15693

The standard for so-called vicinity contactless labels, with a somewhat greater range, integrated into the NFC universe under the name NFC-V and corresponding to NFC Forum Type 5. It is encountered in industry, logistics and certain specialized labels.

ISO/IEC 18092

The founding standard of NFC proper, which defined near-field communication between devices by unifying pre-existing technologies. It is the technology's normative birth certificate.

ISO/IEC 21481 (NFCIP-2)

An overarching standard specifying the communication mode selection mechanism for NFC devices. It acts as a traffic controller, allowing an active NFC interface to automatically detect whether it should switch to ISO/IEC 14443 (Proximity), ISO/IEC 15693 (Vicinity), or ISO/IEC 18092 (Peer-to-Peer) mode without interfering with neighboring systems.

ISO/IEC 7816

The family of smart-card standards, contact cards originally, from which NFC reuses essential building blocks, first among them the APDU dialogue. It connects the contactless world to decades of engineering behind banking and identity cards.

KEY DERIVATION FUNCTION (KDF)

A cryptographic algorithm that computes unique session keys from master keys and contextual data like UIDs or nonces.

KEY DIVERSIFICATION

A cryptographic strategy where individual encryption keys for each specific tag are derived dynamically from a master key using unique variables like the tag's factory serial number, ensuring that compromising one tag does not compromise the entire system.

KEY SETS / MULTIPLE KEYSETS

A mechanism in DESFire EV2 and EV3 allowing applications to hold up to 16 distinct sets of access keys simultaneously, facilitating seamless key rolling and field key rotation without breaking existing reader deployments.

KEY VERSIONING

A metadata byte attached to each key stored within a DESFire chip indicating its generation version, helping software systems manage key updates across large distributed reader fleets.

KEYS A AND B (MIFARE CLASSIC)

A pair of authentication keys protecting each memory sector of a MIFARE Classic chip, with distinct rights, reading or writing depending on the configuration. A legacy of another era of security, this proprietary mechanism is today considered fragile, which explains the migration of serious systems toward modern chips. See the full MIFARE Classic chip page.

LANDING PAGE

The online page toward which the link encoded in a tag points: profile, menu, welcome guide, product sheet. In the modern architecture of NFC, it is the page that carries the richness and freshness of the content, the tag being merely the path that leads there.

LINEAR RECORD FILE

A DESFire file structure comprised of fixed-size records appended sequentially, useful for storing structured list data like digital coupons or ticket logs.

LLCP (LOGICAL LINK CONTROL PROTOCOL)

An NFC Forum protocol layer that manages communication channels between two active devices operating in Peer-to-Peer mode. Sitting above the physical layer, LLCP enables multiplexed, reliable, or connectionless data transfers between apps on different phones.

LOAD MODULATION

The technique by which a tag, deprived of any transmitter of its own, answers the reader: by absorbing more or less energy from the field in a coded rhythm, it imprints variations upon it that the reader decodes. The classic image is that of a mirror making a lamp's light flicker in reply.

LOCATION TRACKER

A small active, battery-powered device that reports its position by leaning on networks of third-party devices. Not to be confused with an NFC tag, which locates nothing: the two objects actually complement each other on the same piece of luggage, the tracker saying where the object is, the tag letting whoever finds it contact its owner.

LOCK BITS

Special areas of a chip's memory whose flipping, irreversible by construction, permanently forbids writing. They are what makes the switch to read-only permanent: no software can ever flip them back.

LOCKING

The operation that permanently forbids writing to a tag by flipping its lock bits, reading remaining free. Irreversible by construction, it protects public tags from hijacking and pairs ideally with a redirect link, which preserves the content's freedom to evolve.

LOGICAL CHANNEL

A virtual communication path established over a single physical link, allowing a reader to interact with distinct smart card applications concurrently.

MAC (MESSAGE AUTHENTICATION CODE)

A short cryptographic checksum attached to dynamic tag URLs or data frames that proves the content was generated by a genuine chip possessing the correct secret key and has not been altered in transit.

MAGIC CARD (WRITABLE UID)

A nickname for the special chips whose unique identifier, normally engraved for life, can be rewritten. Designed for testing and security research, they also serve to bypass controls founded on the identifier, an illegal use as soon as it targets other people's systems; serious systems, moreover, know how to detect them.

MANCHESTER AND MILLER ENCODING

The digital line-coding schemes used to format data bits prior to RF modulation. ISO/IEC 14443 Type A relies on Modified Miller encoding for downlink communication (reader to tag) and Manchester encoding for uplink communication (tag to reader).

MEMORY GRANULARITY

The smallest addressable byte block that can be individually read, written, or password-locked within a tag's non-volatile memory layout.

MEMORY PAGES AND BLOCKS

The internal division of chip memory into small addressable units, four-byte pages on common tags, blocks and sectors on other families. The user never accesses them directly, applications taking care of it, but the vocabulary surfaces in expert-mode reads.

MF3ICD40

The commercial part number for the original, first-generation MIFARE DESFire chip introduced in 2002, which relied strictly on 3DES encryption before being succeeded by EV1. See the full MIFARE DESFire EV1 chip page, its direct successor.

MICRO-ANTENNA

An exceptionally small antenna loop (under 10 mm in diameter) designed for ultra-compact devices like smart rings or medical implants.

MIFARE

A very widespread commercial family of contactless chips, whose members dissolve unevenly into NFC: NFC Forum compliant ranges coexist with historical references, such as the MIFARE Classic, whose proprietary protocol is not uniformly supported by smartphones. Hence a purchasing rule: for consumer NFC use, check the chip's NFC Forum compliance. See the full MIFARE Classic chip page; all chip pages of the family are listed in the NFC chips knowledge base.

MIFARE DESFIRE

The secure branch of the MIFARE family, equipped with embedded cryptography and an application-based organization, reigning over transport ticketing and demanding access control. It falls under NFC Forum Type 4 and plays in a different category from the content tag. Detailed chip pages: MIFARE DESFire EV1, EV2, EV3 and DESFire Light.

MIFARE ULTRALIGHT

The historical reference of the lightweight chip without cryptography, direct ancestor of the NTAG line with which it shares membership of Type 2. It is encountered in short-lived ticketing and disposable uses. Detailed chip pages: MIFARE Ultralight, Ultralight C and Ultralight EV1.

MIME (RECORD)

A type of NDEF record carrying data qualified by its MIME type, in the manner of an attachment: a small visual, application data. Rarely used on consumer tags, the available memory lending itself poorly to it, it mainly serves exchanges between applications.

MIRROR (FUNCTION)

A function of certain chips consisting in automatically reflecting, within the content that is read, internal information such as the unique identifier or the read counter, inserted at a chosen spot in the link. It enables links that change at every read, the foundation of counting and dynamic authentication mechanisms. On NTAG chips, the UID mirror inserts the 7-byte serial number as 14 hexadecimal characters and the counter mirror inserts the 24-bit tap counter, at a configurable position in the link.

MOBILE ACCEPTANCE (TAP TO PHONE)

A family of solutions turning an ordinary smartphone into a payment terminal, the customer's card being presented directly against the merchant's phone. It illustrates the reversibility of phones' NFC, able to play the card as well as the terminal, and lowers the cost of entry to card acceptance for small businesses.

MULTI-RECORD NDEF MESSAGE

An NDEF message housing two or more distinct records packaged inside a single container, allowing a single scan to trigger multiple complementary actions (such as adding a contact while launching a website).

MULTIPLE FILE ACCESS RIGHTS

An authorization matrix in DESFire EV2/EV3 mapping up to 8 different access keys to specific actions (Read, Write, Read&Write, ChangeAccessRights) on a single file.

MUTUAL AUTHENTICATION

A security handshake where both the reader and the card cryptographically prove their identities to each other before exchanging sensitive data. It is the entry point to the secure channels of MIFARE DESFire, ICODE DNA and NTAG 424 DNA.

NDEF FORMATTING

The preparation of a chip's memory so that it can accommodate NDEF records, by writing into it the structures phones expect to find. Consumer tags are delivered ready to use; formatting concerns, in practice, only certain bare chips or ones diverted from other uses.

NDEF (NFC DATA EXCHANGE FORMAT)

The exchange format standardized by the NFC Forum, the common language of all tag content: an NDEF message, composed of typed records, that every smartphone knows how to interpret. It is the key to the universality of tags between Android and iPhone.

NEAR FIELD

The zone immediately surrounding an antenna, where a magnetic field dominates that does not propagate afar and whose intensity collapses with distance. NFC, literally near field communication, is deliberately built within this zone: its range of a few centimeters follows from it, as does its proximity-based security.

NFC-A, NFC-B, NFC-F, NFC-V

The names of the four technology families NFC devices know how to practice, resting on the underlying standards: NFC-A and NFC-B for the two variants of ISO/IEC 14443, NFC-F for FeliCa technology, NFC-V for ISO/IEC 15693. A tag's technical sheet states the family it belongs to.

NFC-DEP (NFC DATA EXCHANGE PROTOCOL)

The transport-level protocol defined in ISO/IEC 18092 for Peer-to-Peer communications. It sets the frame format and handshaking procedures required for two active NFC devices to negotiate transmission parameters and exchange raw data blocks directly.

See also: ISO/IEC 18092, peer-to-peer, LLCP.

NFC FORUM

The international body bringing together the technology's stakeholders, which issues the specifications ensuring interoperability: the NDEF format, tag types, device requirements. The mention of NFC Forum compliance on a chip is the pledge of its full citizenship within the ecosystem.

NFC FORUM CERTIFICATION

The program by which the NFC Forum attests the compliance of devices and components with its specifications, at the end of standardized test campaigns. For the buyer, certification is a pledge of real interoperability, beyond the promises of product sheets.

NFC FORUM TAG TYPES (TYPE 1 TO TYPE 5)

The classification by which the NFC Forum orders compliant tags into five types, according to their underlying technologies and their ways of managing NDEF. Type 2, home of the common consumer chips, dominates daily life; Type 5 covers vicinity labels, Type 3 the FeliCa universe.

NFC (NEAR FIELD COMMUNICATION)

A wireless communication technology operating in the near field, at 13.56 megahertz over a few centimeters, between an active device and a passive tag, or between two devices. Heir to high-frequency RFID, it was standardized for consumer use, from the smart tag to mobile payment.

NFC PAIRING

The use of NFC as a matchmaker between two Bluetooth devices: the NFC touch transmits the connection information, then Bluetooth takes over for the long-haul exchange. It is the principle behind speakers one connects by touching them with a phone.

NFC READ SHIELD (SKIMMING PROTECTION)

A protective sleeve, wallet lining, or card incorporating a thin layer of continuous metal or active jamming circuitry. By reflecting or absorbing 13.56 MHz magnetic fields, it prevents unwanted readers from powering passive cards and performing unauthorized reads or skimming.

See also: anti-metal tag, eavesdropping.

NFC TOOLS

The reference application for reading, writing and managing tags, published by Wakdev and available on Android and on iPhone. Its two versions share the essentials, detailed reading, writing of common records, erasing, locking, copying, with different advanced perimeters, Apple's rules framing access to the chip more strictly on iOS.

NTAG

The chip family that has become the de facto standard of the consumer tag, compliant with NFC Forum specifications and declined in references that differ essentially only in their usable memory, from about one hundred and forty-four bytes at the entry level to nearly nine hundred at the top. All chip pages of the family are listed in the NFC chips knowledge base.

NTAG 213 TT (TAMPER TAPE)

A specialized variant of the NTAG213 chip featuring a secondary physical sensing loop that permanently alters the readable NDEF payload if the seal or label is severed. See the full NTAG213 TT chip page.

NTAG 223 / 224 DNA

Advanced generations of security-focused NTAG chips providing cryptographically signed NDEF messages, dynamic authentication, and encrypted data channels for brand protection.

NTAG 424 DNA / 424 DNA TT

The gold standard for secure consumer tags, featuring AES-128 cryptographic operations, Secure Unique NDEF Messaging (SUN), and optional physical tamper-detection loops. It generates a unique, verifiable cryptographic URL on every tap, protecting against cloning and URL sniffing without requiring a dedicated app. See the full NTAG424 DNA chip page.

NTAG 5 BOOST / LINK / SWITCH

A modular series of industrial-grade NFC Forum Type 5 / ISO 15693 chips designed for sensor logging, energy harvesting, and direct electronic control interfaces.

NTAG I2C PLUS

A dynamic bridge chip family combining standard NFC Forum Type 2 wireless tag access with a high-speed wired I2C interface, featuring zero-power memory access and SRAM pass-through.

NULL RECORD

An empty NDEF record containing no type or payload, used primarily as a placeholder in memory, as a terminator signal, or to wipe memory areas during editing without altering the overall memory structure.

OFF-FIELD SRAM PASS-THROUGH

An operational mode in dynamic NTAG chips where an internal 64-byte SRAM buffer acts as a fast data pipeline between an NFC smartphone and a host device, bypassing slower EEPROM writes.

ON-CHIP SENSOR

A miniature sensor (such as a temperature or moisture sensor) fabricated directly onto the silicon wafer of an NFC chip, allowing passive environmental logging powered purely by a smartphone tap.

OOB (OUT-OF-BAND) PAIRING

A security and setup pattern where sensitive configuration or authentication data (such as Bluetooth PINs or Wi-Fi credentials) is exchanged over an "out-of-band" physical channel (namely an NFC tap) before establishing the main high-speed connection.

See also: handover, NFC pairing, Bluetooth.

OPERATING MODES

The three distinct ways an NFC-enabled device can function: Reader/Writer mode (reading or encoding passive tags), Card Emulation mode (acting like a contactless smart card for payments or ticketing), and Peer-to-Peer mode (exchanging data directly with another active device).

See also: card emulation, peer-to-peer, reader.

ORIGINALITY SIGNATURE

A cryptographic signature written at the factory into certain chips, allowing verification that they truly come off the announced manufacturer's lines. A tool against counterfeit chips, it authenticates the component, not the product that carries it. On NXP chips (NTAG, ICODE), it takes the form of an ECC signature engraved in read-only memory.

OTP MEMORY AREA (ICODE)

A designated One-Time Programmable memory zone in ICODE chips where individual bits can be flipped from 0 to 1, but never back, useful for permanent serialization or batch logging.

OTP (ONE TIME PROGRAMMABLE)

The qualifier for memory areas programmable a single time: their state, once changed, never reverts. Lock bits are the emblematic example; it is this physical property that makes the switch to read-only irreversible.

OVERFLOW / UNDERFLOW PROTECTION

Built-in protection logic applied to DESFire Value Files preventing arithmetic operations (debits or credits) from exceeding maximum limits or dropping below zero.

PACK (PASSWORD ACKNOWLEDGEMENT)

A 2-byte code returned by an NTAG chip to the reader upon receiving a correct password, confirming successful authentication before access to protected pages is granted.

PAGE ADDRESSING (4-BYTE PAGES)

The fundamental internal layout of Type 2 NTAG chips, where memory is divided into small 4-byte (32-bit) addressable units named Page 0 through Page N.

PARITY BIT

An extra bit appended to a binary data string during transmission to ensure that the total count of set bits is always even or odd, offering a fast, low-level line error check for individual bytes.

PASSIVE

Said of a tag deprived of any energy source of its own: electrically dead at rest, it lives only for the duration of a read, powered by the reader's field. From this passivity flow the longevity, the thinness and the modest cost of tags, as well as their reduced range.

PASSIVE SENSOR INTERFACE (ICODE)

An integrated hardware bridge on specialized ICODE chips allowing direct connection to external passive sensors (e.g., cold-chain temperature monitoring) powered entirely by the reader's magnetic field.

PASSWORD PROTECTED EAS

A security feature requiring a 32-bit secret password to enable or disable the EAS alarm flag, preventing shoplifters from turning off theft protection using portable NFC devices.

PASSWORD PROTECTION

A write protection, offered by common chips, in which any modification requires a password stored in the chip itself. Reversible for whoever holds the key, it becomes permanent for whoever loses it; its implementation belongs to the advanced functions, where the Android ecosystem remains the most at ease.

PAYLOAD

The content proper of an NDEF record, once its packaging structure is deducted: the link's address, the message's text, the contact card's fields. The size displayed by writing applications corresponds to the payload plus that structure.

PCD (PROXIMITY COUPLING DEVICE)

The technical designation defined in ISO/IEC 14443 standards for the reader device (such as a smartphone or payment terminal) that generates the radio field and communicates with proximity cards.

PEER-TO-PEER (P2P)

NFC's historical mode of direct exchange between two devices, popularized for a time for sharing content between phones and then abandoned by mainstream use in favor of other technologies. It survives in the standard more than in practice.

PICC MASTER KEY (PMK)

The absolute root encryption key controlling the entire DESFire chip; required to execute global card operations like changing card configuration, formatting memory, or deleting all applications.

PICC (PROXIMITY INTEGRATED CIRCUIT CARD)

The technical designation defined in ISO/IEC 14443 standards for the contactless card, tag, or target device that dialogues with a PCD reader.

PRE-ENCODING

A service consisting in delivering tags already written, and where applicable locked, with contents supplied by the customer. It shifts serial production and its quality control to the supplier, and makes full sense as soon as volumes grow or each tag must receive a link of its own.

PRIVACY MODE (ICODE)

A protective state where the ICODE chip conceals its true 64-bit UID and blocks all standard memory reads until a valid 32-bit privacy password is supplied by the reader.

PROTOCOL PARAMETER SELECTION (PPS)

A protocol negotiation command used in ISO/IEC 14443 to adjust data rates between card and reader after initial connection.

PROXIMITY CHECK (DESFIRE)

A security mechanism in DESFire EV2 and EV3 that measures the ultra-precise round-trip time of radio frames between card and reader to block man-in-the-middle and relay attacks.

PROXIMITY VS. VICINITY

The normative classification dividing short-range and medium-range HF technologies. Proximity (ISO/IEC 14443) targets communication within 10 centimeters and forms the core of mobile payments and NTAG chips. Vicinity (ISO/IEC 15693 / Type 5) extends operation up to 1 meter for industrial and library applications.

See also: ISO/IEC 14443, ISO/IEC 15693, range.

PWD (32-BIT PASSWORD)

A 4-byte secret key written to an NTAG's configuration memory that restricts write access (or both read and write access) to designated memory pages.

QR CODE

A printed two-dimensional barcode, functional cousin of the NFC tag for opening a link, read by the camera where NFC is read by simple approach. The two happily cohabit on the same medium, the code ensuring universal accessibility, the tag offering the most direct gesture.

QUIET COMMAND / STAY QUIET

A protocol instruction sent by an ISO 15693 reader to instruct a specific, already-identified ICODE tag to temporarily stop responding, allowing the reader to detect remaining unread tags in the field.

RANDOM UID

An option of certain chips consisting in presenting, at every session, an identifier drawn at random in place of the fixed serial number. Designed to protect privacy, it prevents a cardholder from being tracked through the identifier of their card; it does, however, make the chip unsuitable for uses founded on a stable identifier. On MIFARE DESFire, the mode returns a random 4-byte identifier at each session.

RANGE

The maximum communication distance between reader and tag, on the order of a few centimeters, imposed by the physics of the near field and embraced by the standard. A limit in appearance, it founds NFC's proximity security and the intentional character of the gesture.

READ COUNTER

An internal counter offered by certain chips, which increments at every read of the tag. Combined with the mirror function, it allows the number of reads to be reflected in the encoded link, the basis of visit counting without any additional electronics. On NTAG21x chips this counter is 24 bits wide.

READ MULTIPLE BLOCKS

An ISO 15693 standard command supported by ICODE chips that enables a reader to fetch up to 32 contiguous memory blocks in a single radio transaction.

READ-ONLY

The state of a tag whose writing has been permanently forbidden by locking: its content can be read freely, forever, but can never again be modified. It is the reference protection for tags exposed to the public.

READER

Any active device generating the magnetic field and leading the dialogue with tags: smartphone, payment terminal, kiosk, industrial reader. In the reader and tag couple, it is the one providing the energy and taking the initiative; the tag only answers.

READING ZONE

The precise spot on the smartphone where the NFC antenna sits, the upper edge of iPhones, the back and upper half of most Androids. Knowing it transforms the experience: nearly all laborious reads are merely missed rendezvous between two antennas.

RECORD

The elementary building block of a tag's content in the NDEF format: each record carries a label declaring its nature, link, text, contact, Wi-Fi configuration, and its payload. A tag contains one or more records, within the limits of its memory; on spontaneous reading, phones generally trigger only the action of the first one.

RECORD FILE (DESFIRE)

A high-level DESFire file abstraction containing a structured sequence of fixed-size entries, supporting commands like Read Records or Append Record.

REDIRECT LINK

An intermediate address, controlled by the tag's owner, which forwards to the landing page of the moment. Encoding a redirect rather than a raw address dissociates forever the tag, immutable and lockable, from the content, editable at will: it is the cornerstone of durable deployments.

RELAY ATTACK

An attack scenario consisting in artificially extending, by means of two accomplice devices, the dialogue between a card and a terminal that are in fact far apart. It targets transactional systems, not simple content tags, whose reading is free by nature; payment protocols oppose it with dedicated countermeasures, timing measurements in particular.

RESONANCE

The phenomenon by which the circuit formed by the antenna and the chip, tuned to the working frequency, responds with maximum efficiency to the reader's field, in the manner of a tuning fork vibrating at its note. It is resonance that lets a tiny tag capture enough energy to live.

RESTRICTED PAGE ACCESS

An access rule where reading or modifying specific memory pages requires executing a successful PWD/PACK authentication exchange prior to sending standard read/write commands.

RF FIELD STRENGTH (H-FIELD)

The magnetic field intensity generated by a reader's antenna, measured in amperes per meter (A/m). ISO/IEC standards dictate that a reader must supply a minimum field strength (typically 1.5 A/m to 7.5 A/m) throughout its operating volume to reliably wake up passive tags without damaging them.

RFID-BLOCKING SLEEVE

A pouch or wallet incorporating shielding that blocks the contactless communications of the cards it contains. Effective for peace of mind, it is also a classic cause of mute NFC tags and cards: nothing can be read through it, by definition.

RFID (RADIO FREQUENCY IDENTIFICATION)

The vast family of radio-frequency identification technologies, declined across several frequency bands and ranges, queen of logistics, access control and animal identification. NFC is its direct descendant, born of its high-frequency branch and standardized for the general public.

ROLLBACK MECHANISM

The automatic hardware recovery system inside DESFire chips that reverts memory to its last known good state if RF power is lost mid-transaction.

RTD (RECORD TYPE DEFINITION)

The set of definitions published by the NFC Forum for the standardized record types, text, URI and smart poster in particular. It is this shared frame of reference that guarantees a record written here will be understood everywhere.

SAK (SELECT ACKNOWLEDGE)

The value a Type A chip returns at the end of its selection by the reader, informing on its nature and capabilities. Together with the ATQA, the SAK serves the fine technical identification of chips, a matter of diagnostics more than of everyday use.

SAM (SECURE APPLICATION MODULE)

A dedicated cryptographic smart card chip (often built directly into payment terminals, transit turnstiles, or industrial readers) that holds master encryption keys. The SAM handles key verification and mutual authentication locally with tags (like MIFARE DESFire) without exposing secret keys to host software.

SCAN SESSION

On iPhone, the NFC operating window opened by an application: the system sheet that rises from the bottom of the screen, invites you to bring the tag close, and closes upon success, failure or expiry. Every application-driven NFC operation on iOS lives inside such a session, the concrete expression of the supervision Apple intends.

See also: Core NFC, background tag reading.

SECRET KEY STORAGE

A dedicated, hardware-isolated RAM/EEPROM zone inside a DESFire chip protected by anti-probing shields, where AES and 3DES keys reside inaccessible to software reads.

SECURE CHANNEL (DESFIRE)

An encrypted, integrity-protected radio session established between a reader and a DESFire chip following successful mutual AES authentication.

SECURE ELEMENT (SE)

A tamper-resistant hardware component, present notably in smartphones (as an embedded eSE or within the SIM), where sensitive operations such as contactless payment are confined. It has nothing in common with an ordinary tag: it is a certified electronic safe holding tokenized bank credentials, access badges and transit passes, out of reach of everyday applications.

SECURITY KEY (FIDO)

A small strong-authentication device presented to one's phone, often via NFC, to validate a sign-in according to the FIDO standards. It illustrates a trusted NFC, founded on embedded cryptography, at the opposite end from the simple content tag.

SELECT COMMAND (ISO 15693)

An instruction that locks a reader's communication focus onto a single, specific ICODE tag using its 64-bit UID, ignoring all other tags present in the magnetic field.

SERIALIZATION

The serial encoding of tags each receiving data of its own, an individualized link most often, as opposed to the duplication of identical content. It demands a production discipline, a correspondence table and per-unit verification, and founds the uses where each tag must be distinguishable, unit tracking or personalized pages.

SHORTCUTS (APPLE)

The automation application built into the iPhone, whose personal automations can be triggered by the reading of an NFC tag, identified by its chip, content unnecessary. It turns the tag into a physical button commanding sequences of actions, the intelligence residing in the phone.

SILICON SERIAL NUMBER (64-BIT UID)

The factory-engraved 8-byte unique identifier permanently burned into every ICODE chip, including manufacturer codes (NXP = 0x04) and standard ISO 15693 header flags.

SMART LABEL INLAY

The intermediate physical product consisting of an ICODE silicon chip mounted onto a flexible antenna substrate, ready to be converted into paper labels or hangtags.

SMART POSTER

A type of NDEF record combining a link with accompanying information, a title in particular, originally designed for interactive posters. It survives in writing catalogues, but modern use prefers the plain link, lighter and interpreted everywhere.

SNEP (SIMPLE NDEF EXCHANGE PROTOCOL)

An NFC Forum protocol running on top of LLCP that allows two Peer-to-Peer devices to push or pull NDEF messages directly to each other. It was the underlying protocol formerly used by features like Android Beam.

ST25

A family of NFC chips from a major European semiconductor manufacturer, covering in particular Type 4 and Type 5 references. Its presence in technical sheets is a reminder that the market does not boil down to a single line: several compliant families coexist, interoperable by construction. Detailed chip pages: ST25TA, ST25TB, ST25TN, ST25TV and LRI2K.

See also: NTAG, ICODE, NFC Forum tag types.

STANDARD DATA FILE

A basic DESFire file type presenting memory as a raw, contiguous array of bytes, suitable for storing arbitrary payload data like photos or text.

STATIC LOCK BITS (NTAG)

System bits located in Page 2 of an NTAG chip that permanently freeze access to lower memory pages (Pages 0 to 15), including the capability container and early NDEF bytes.

SUBCARRIER

An auxiliary frequency (typically 848 kHz), generated by the tag from the reader's carrier, onto which it imprints its response by load modulation. A detail of radio architecture invisible in use, it explains how the tag's faint response remains distinguishable from the reader's powerful signal.

SUBSTRATE

The carrier material on which the inlay is mounted and which gives the tag its final form: the plastic film of stickers, the PVC of cards, the wood, metal or ceramic of crafted objects. It determines the tag's physical resistance, the true limiting factor of its lifespan.

See also: inlay, anti-metal tag, encapsulation.

SUN / SDM (SECURE UNIQUE NDEF / SECURE DYNAMIC MESSAGING)

Dynamic authentication mechanisms offered by specialized chips: at every read, the tag inserts into its link a cryptographic code verifiable by the destination server, rendering the copying of the content useless. It is the serious answer to the need for product authentication, where the standard tag can only offer declarative traceability. Present on NTAG 424 DNA and MIFARE DESFire EV3; configurable offset pointers place the UID, counter and MAC in the URL, and servers commonly verify a truncated 8-byte MAC to keep links short.

See also: mirror (function), encryption, cloning.

SWP (SINGLE WIRE PROTOCOL)

A single-wire physical interface standard connecting an NFC controller chip directly to a SIM/UICC card inside a mobile phone, enabling the SIM card to act as a hardware Secure Element for contactless transactions.

See also: secure element, card emulation.

SYSTEM INFORMATION (ICODE)

A standardized status response returned by an ICODE chip detailing its memory block size, total block count, UID, IC reference code, and lock status bits.

TAG

The established name of the NFC label: the whole formed by the chip, its antenna and its carrier, a passive object waiting to be read. Sticker, card, key fob, token or implant within an object: the tag takes every shape, for one and the same function.

TAG SECTOR LOCKING

The granular access protection feature found on advanced multi-sector chips (such as MIFARE Classic or DESFire) that allows administrators to freeze or lock specific memory sectors independently while leaving other sectors re-writable for future applications.

TAMPER EVIDENCE LOOP (ICODE)

A physical sensing circuit built into advanced ICODE labels that permanently sets an internal digital flag if the antenna or label substrate is cut, torn, or peeled.

TAMPER-EVIDENT TAG

A tag in which a conductive loop, broken when the packaging is opened or the medium peeled off, detectably changes the state reported at reading. It turns NFC into a witness of integrity, for sealing bottles, packaging or equipment.

TEXT (RECORD)

A type of NDEF record carrying free text, accompanied by a language code that phones can exploit. With no associated action, it displays rather than triggers: it is reserved for notes, instructions and complements, action remaining the business of the link.

TLV (TYPE LENGTH VALUE)

The elementary structure, type then length then value, by which the memory of certain tags organizes its data blocks, including the NDEF message. A piece of internal plumbing, encountered in expert-mode reads, and which applications handle for you.

TNF (TYPE NAME FORMAT)

The header field of every NDEF record indicating the family of its type, NFC Forum standardized type, MIME type or external type in particular. Plumbing of the format, encountered in detailed reads, which explains how phones know what to do with each record.

TOKENIZATION

A security mechanism of mobile payment consisting in replacing the card's real number with a token dedicated to the device, the only thing transmitted during transactions. The merchant never sees the true number, and a compromised token is revoked without replacing the card: it is one of the reasons paying by phone is no less safe than by card.

TRANSACTION MAC (DESFIRE)

A cryptographic checksum generated by the DESFire chip at the conclusion of a complex multi-step transaction, providing mathematical proof to backend servers that a transaction occurred successfully.

TRANSACTION TIMER

A security feature introduced in DESFire EV3 that sets a strict microsecond timeout for completing authentication and file modification, thwarting man-in-the-middle attacks.

TYPE 2 TAG COMPLIANCE

The foundational NFC Forum standard governing the NTAG21x and NTAG I2C lines, dictating 4-byte page structures, anti-collision rules, and basic command sets.

TYPE 5 TAG (NFC FORUM)

The official NFC Forum classification designating long-range vicinity tags based on ISO/IEC 15693 technology, of which NXP's ICODE family is the dominant industry implementation.

UID CASCADE LEVEL

The multi-step process defined in ISO/IEC 14443 Type A through which a reader retrieves a chip's unique serial number. Because legacy UIDs were 4 bytes and modern UIDs are 7 bytes (or rarely 10 bytes), the anti-collision procedure operates across up to three "cascade levels" to read the full identifier.

See also: UID, anti-collision, ISO/IEC 14443.

UID (UNIQUE IDENTIFIER)

The chip's serial number (typically 7 bytes on standard tags), engraved at manufacture, unique in the world, immutable and readable by all. It tells tags apart, serves as a trigger for automations and as a landmark for deployments, but constitutes neither a secret nor, on standard tags, an element that can be reproduced.

URI PREFIX

An abbreviation mechanism provided by the NDEF format, which replaces the most common beginnings of addresses with a single-byte code. It is thanks to it that a link weighs less than it appears to, and one of the reasons to prefer addresses with standard prefixes.

URI / URL (RECORD)

The most widely used type of NDEF record, carrying an address in the broad sense: a web page, but also a call, email, message or geolocation command, depending on the prefix employed. It is the vehicle of NFC's king use, the opening of a link.

See also: record, landing page, URI prefix.

USABLE MEMORY CAPACITY

The number of bytes actually available for the user's data, lower than the chip's raw memory, part of which is reserved for internal operation. It is the only value that matters when sizing a project; it is expressed in hundreds of bytes on consumer chips. An NTAG213, for instance, carries 180 bytes of raw memory but only 144 usable, the difference going to capability container, lock bits and system registers.

USER MEMORY (PAGES 04H+)

The contiguous block of memory pages starting at address 0x04 where user NDEF payloads (links, text, contacts) are encoded on standard consumer NTAG chips.

UWB (ULTRA WIDEBAND)

A fine-location radio technology embedded in certain phones and trackers, capable of measuring distances and directions. It has nothing in common with NFC beyond their proximity on spec sheets: to NFC the intentional contact, to UWB the precise localization.

VALUE FILE

A specialized DESFire file structure designed specifically for electronic purse applications, storing numerical balances and enforcing built-in Credit, Debit, and ReadBalance commands.

VCARD

The standardized format of contact cards, understood by every phone address book. Encoded on a tag, the vCard allows contact details to be saved in one gesture, with no network required; hungry for bytes, it calls for chips with comfortable memory and freezes the data at the moment of writing.

VICC (VICINITY INTEGRATED CIRCUIT CARD)

The technical designation defined in ISO/IEC 15693 for medium-range contactless transponders (vicinity tags) operating up to 1 meter from a reader.

VICINITY RANGE (1 METER)

The extended operational communication range (up to 1 meter) achievable by pairing ISO 15693 ICODE labels with high-power industrial readers and large antennas.

VIRTUAL CARD ARCHITECTURE (VCA)

An architectural layer in DESFire EV2/EV3 allowing a single physical chip (or smartphone dynamic emulation target) to present multiple virtual smart card profiles to different readers cleanly.

WALLET (DIGITAL WALLET)

A system application gathering payment cards, transit passes, tickets and keys, presented to the terminal by NFC. It is the consumer showcase of card emulation, and the place where the phone's NFC most often works without its name even being spoken.

WEB NFC

An interface allowing a web page to read and write tags directly from the browser, with no application installed. Its support remains partial, essentially confined to certain browsers on Android, which makes it a supporting tool rather than a universal foundation.

WI-FI (RECORD)

A type of NDEF record containing the credentials of a wireless network, name, security type and password. Android devices exploit it by offering the connection in one gesture; iPhones do not interpret it in the same way, which imposes, for a mixed audience, a complement in text or link form.

WIRELESS CHARGING (NFC-WLC)

An official NFC Forum specification enabling an active NFC antenna to transfer small amounts of power (up to 1 watt) to tiny, battery-powered IoT devices (like wireless earbuds, styluses, or fitness trackers) over the 13.56 MHz link, combining power transfer and data communication on a single coil.

WRAPPED APDU (DESFIRE)

A transmission method where native DESFire commands are wrapped inside standard ISO/IEC 7816-4 APDUs, allowing standard PC/SC smart card hardware to interface with DESFire chips without proprietary drivers.

WRITE CYCLES (WRITE ENDURANCE)

The number of rewrites a chip's memory can endure before wearing out, guaranteed by manufacturers at around one hundred thousand cycles on common references (up to 500,000 on some NTAG references). Reading, for its part, wears nothing at all. Set against real use, where a tag is written a handful of times in its life, this limit is purely theoretical.

WRITE MULTIPLE BLOCKS

A command allowing a reader to write identical or sequential data across several contiguous memory blocks in an ICODE chip during a single operation, accelerating encoding workflows.

ZERO-POWER DATA RETENTION (ICODE)

The guaranteed physical storage duration (typically 50 years or more) during which an unpowered ICODE chip retains its EEPROM contents under standard environmental conditions.

ZERO-POWER DISPLAY INTEGRATION

An emerging architectural combination pairing dynamic NFC chips with e-ink displays, where the energy harvested from a smartphone tap is used both to update the display content and rewrite the tag's internal memory.

ZERO-POWER PASS-THROUGH

A functional mode on dynamic NTAG chips where energy harvested from a scanning phone completely powers both the NFC interface and the attached microcontroller during data transfer.

Knowledge base