Near Field Communication (NFC) is a set of short-range wireless technologies, typically requiring a distance of 4cm or less. NFC operates at 13.56mhz, and at rates ranging from 106 kbit/s to 848 kbit/s. NFC communication always involves an initiator and a target. The initiator actively generates an RF field that can power a passive target. This enables NFC targets to take very simple form factors such as tags, stickers or cards that do not require power. NFC peer-to-peer communication is also possible, where both devices are powered.

Compared to other wireless technologies such as Bluetooth or WiFi, NFC provides much lower bandwidth and range, but enables low-cost, un-powered targets and does not require discovery or pairing. Interactions can be initiated with just a tap.

Tags can range in complexity, simple tags just offer read/write semantics, sometimes with one-time-programmable areas to make the card read-only. More complex tags offer math operations, and have cryptographic hardware to authenticate access to a sector. The most sophisticated tags contain operating environments, allowing complex interactions with code executing on the tag.