Electronic tagging, or ET, is the process of attaching a device to something to track its location and status. The device can come in several forms: bracelet, anklet, dog tag, or microchip. ET is most commonly used in farming to track livestock and other animals. It can also be used to track people, usually by police, for criminals under house arrest. The device's functionality is based around the use of GPS and RFID (radio frequency identification).
How Tagging Works: GPS
Electronic tagging works based on two types of networks: GPS and RFID. GPS, which is similar to the GPS in automobiles, uses satellites to triangulate the position of the tag. The satellite relays information on the coordinates of the tag to the tag's owner. Devices using this type of network use a single-chip-based system that works to broadcast or transmit the data to the satellite. In regard to anklet- or bracelet-style tags, the device broadcasts to a central hub, which is then connected to a phone line and transmits the data to the owner.
How Does Tagging Work: RFID
Another method is RFID (radio frequency identification). Unlike the chip-based GPS, these units can come in several forms (usually a compact circuit). RFID tags have two components: (1) an integrated circuit for processing the tags information and (2) an antenna for receiving and broadcasting information. Because of the limited technology required for their function, the tags can be almost any size. In livestock and cattle, an implant is inserted into the animal's tissue; this protects the tag from damage or loss.