'''Radio frequency identification''' (RFID) is a method based on storing and automatically retrieving identification data transmitted over the radio frequency spectrum. Devices called "[[RFID transponders]]", "RFID tags " or "chips" are [[transponder]]s that transmit the stored information to a remote sensing device. An RFID tag can be attached into a product, or implanted in an [[animal]], or a [[homo sapiens|person]], for the purpose of identification. RFID tags may require no internal power source, in which case they are called passive tags, whereas active tags require a power source. RFID is used to time sporting events, inventory control, and the collection of tolls on highways.
The increasing use of RFID tags has come under intense scrutiny, especially as companies are beginning to use them to track [[consumer]] purchases in stores, and as the development of injectable RFID tags (in [[pet]]s, and even in humans) is becoming a reality. Many [[Christian]]s see this as related to the [[Mark of the Beast]] prophesized in the [[Book of Revelation]], and the book ''[[Spychips]]'' by Katherine Albrecht and Liz McIntyre (ISBN 0-452-28766-9) was a recent best-seller warning of the potential issues with RFID tags.