Radio-frequency identification (RF ID) is the use of a wireless non-contact system that uses
radio-frequency electromagnetic fields to transfer data from a tag attached to an object,
for the purposes of automatic identification and tracking. Some tags require no battery
and are powered and read at short ranges via magnetic fields (electromagnetic induction).
Others use a local power source and emit radio waves (electromagnetic radiation at radio frequencies).
The tag contains electronically stored information which may be read from up to several meters away.
Unlike a bar code, the tag does not need to be within line of sight of the reader and may be embedded
in the tracked object.