An NFC tag is a generic term used to describe all physical tag products that implement NFC functionality. At minimum an NFC tag contains an NFC chip and an antenna, and is often converted into other physical tag products that have additional physical characteristics. NFC tags are passive, meaning that they can not initiate a conversation with an NFC device. NFC tags do not have a battery or other power source; they harvest power from the NFC hardware. The features of an NFC tag are defined by the NFC chip type used in it.