NFC(Near Field Communication) PN532 is a set of standards for smartphones and similar devices to establish radio communication with each other by touching them together or bringing them into close proximity , it builds upon RFID systems by allowing two-way communication between endpoints. Compared with the Bluetooth-compatible, which is also short-range communication technology, NFC operates at slower speeds, but consumes far less power and doesn’t require pairing.
This NFC shield based on the PN532 from NXP, it works on ISM band of 13.56MHz, with the built-in NFC Antenna, the communication range would be about 2cm. You can read and write a 13.56MHz tag with this shield, and communicate with each other or smartphone with the P2P(peer-to-peer) communication.