A RFID Transponder is an ID system that uses small radio frequency identification devices for identification and tracking purposes. An RFID tagging system includes the tag itself, a read/write device, and a host system application for data collection, processing, and transmission. An RFID tag (sometimes called an RFID transponder) consists of a chip, some memory, and an antenna.
RFID tags that contain their own power source are known as active tags. Those without a power source are known as passive tags. A passive tag is briefly activated by the radio frequency (RF) scan of the reader. The electrical current is small—generally just enough for transmission of an ID number. Active tags have more memory and can be read at greater ranges.
Increasingly, RFID tagging is used in supply chain management as an alternative to bar code technology. Although more expensive to use than the bar code stickers, RFID tags don't get dirty, fall off, or require an unobstructed line of sight between the tag and the reader.
There are almost endless possible uses for RFID tagging. Injectable ID chips have been used to track wildlife and livestock for over a decade. RFID transponders have started making their way into the body modification scene.
RFID tagging is somewhat controversial because the tags could, theoretically, be cloned or used for illicit tracking.