What is NFC?
NFC is a contactless technology for exchanging data between devices at very close range. Common examples include holding a phone near a payment terminal, presenting an access card and opening a link from a tag.
How near-field communication works
NFC uses electromagnetic interaction in the near field. Some tags obtain energy from the reader's field without a separate battery. In reader-writer operation, a phone reads a small record from a tag; in card emulation, a device behaves like a card to a compatible reader. A tag may contain a web address, identifier or other application-interpreted information. NFC is better suited to starting short, simple interactions than transferring large files rapidly. For example, tapping a tag can help establish another connection method. NFC support does not mean that a device supports every payment system or card type.
Payments, tags and security
Contactless payment security involves more than the NFC radio link: the payment application, authentication and payment infrastructure also matter. An NFC tag on a poster may merely open a web address and does not carry the same assurances as a payment system. Check the domain of unfamiliar links, avoid unnecessary app installations and use a device lock. Short distance does not eliminate every attack possibility. Card sleeves, antenna placement and metal surfaces can affect reading. Before rewriting a tag, determine whether it is writable and whether others depend on its data; read-only tags may not be changeable.