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WHAT IS RFID?
Radio-frequency identification (RFID) is the
wireless non-contact use of radio-frequency electromagnetic fields to transfer
data, for the purposes of automatically identifying and tracking tags attached
to objects. The tags contain electronically stored information. Some tags are
powered by and read at short ranges (a few meters) via magnetic fields
(electromagnetic induction). Others use a local power source such as a battery,
or else have no battery but collect energy from the interrogating EM field, and
then act as a passive transponder to emit microwaves or UHF radio waves (i.e.,
electromagnetic radiation at high frequencies). Battery powered tags may
operate at hundreds of meters. Unlike a bar code, the tag does not necessarily
need to be within line of sight of the reader, and may be embedded in the
tracked object.

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