Tags can also be used in shops to expedite checkout, and to prevent theft by customers and employees. For example, an RFID tag attached to an automobile during production can be used to track its progress through the assembly line, RFID-tagged pharmaceuticals can be tracked through warehouses, and implanting RFID microchips in livestock and pets enables positive identification of animals. RFID is one method of automatic identification and data capture (AIDC). Unlike a barcode, the tag does not need to be within the line of sight of the reader, so it may be embedded in the tracked object. Active tags are powered by a battery and thus can be read at a greater range from the RFID reader, up to hundreds of meters. Passive tags are powered by energy from the RFID reader's interrogating radio waves. This number can be used to track inventory goods. When triggered by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag transmits digital data, usually an identifying inventory number, back to the reader. An RFID system consists of a tiny radio transponder, a radio receiver and transmitter. Radio-frequency identification ( RFID) uses electromagnetic fields to automatically identify and track tags attached to objects.

For the practice of identifying frequencies of broadcast stations, see Station identification.

Walmart casino chi s