An RFID tag is a microchip combined with an antenna in a compact package; the packaging is structured to allow the RFID tag to be attached to an object to be tracked. RFID stands for Radio Frequency Identification.

The RFID tag's antenna picks up signals from an RFID reader or scanner and then returns the signal, usually with some additional data (like a unique serial number or other customized information).

RFID tags can be very small, the size of a large rice grain. Others may be the size of a small paperback book. The RFID device serves the same purpose as a barcode or a magnetic strip on the back of a credit card or ATM card, it provides a unique identifier for that object.