Contactless

Contactless refers to methods of data exchange or transaction authorization that occur without physical contact between the user’s card, device, or badge and a reader. These systems use short-range wireless communication, typically a few centimeters, to establish a connection and complete an action such as a payment or access check.

The most common technologies are RFID (radio-frequency identification) and near-field communication (NFC). NFC is a mature subset designed for two-way communication and supports powered and passive devices; many contactless cards and tags are passive and are energized by the reader's field. Standards include ISO/IEC 14443 for contactless cards and ISO/IEC 18092 for NFC, with the NFC Forum coordinating interoperability.

Applications include contactless payment cards (credit or debit), mobile wallets and smartphones, transit passes, and access badges for buildings or events. The concept also appears in data sharing between devices via close proximity, such as pairing or brief information exchange.

Security and privacy rely on techniques such as tokenization, dynamic cryptograms, and mutual authentication to prevent cloning and eavesdropping. However, risks include skimming if readers are compromised, relay or proximity attacks, and concerns about tracking users or collecting usage data. Regulations and industry standards aim to protect user data and ensure secure implementations.

Adoption has grown in retail, transportation, and corporate security, driven by convenience and hygiene considerations. Interoperability remains a focus, with ongoing work by ISO/IEC, the NFC Forum, and payment networks to ensure compatibility across cards, devices, and readers.