RFID which is Radio-frequency identification is the technology that uses radio waves to transfer data from an electronic tag or label, usually in an object, through a reader to identify and track the object.
Generally RFID tags can be read from a great distance, beyond the line of sight of a reader.
RFID is similar to NFC which is Near field communication which allows for close contact transfers of information.
Where RFID just requires the radio frequency, NFC requires a touch and is a bit more secure as sensitive information cannot be picked up so readily as being in range with RFID.
RFID is used in EZ PASS readers, the highway, bridge and toll no stop payment system. The technology allows for a person and the object needing to be charged to fly right through readers without stopping. A great way that this technology was hoped to have been used was in grocery stores. It would allow shoppers to pick up and bag items right away then just walk out the store. No lines no waits time. The system is used in Europe but American consumer goods manufacturers have not adapted it nor have retail outlets.
RFIDs can be so light so small and unnoticeable that you may have seen them a thousand times already. An RFID looks like small plastic or sticky paper circuit board. They are currently visible and used as security alarms in stores on DVD cases. (Which is an extreme dumbing down of the technology, if it were used as a payment system there’d be less need for security if it was handled correctly.)
RFID can be used as tracking systems as well. There are people testing 433 MHz battery-powered wristbands and readers, to be sold this fall, in order to protect kids and pets from farm machinery and vehicles. As read in an article by Claire Swedberg http://www.rfidjournal.com/article/view/8691. RFID is useful without battery power, if it doesn’t need to emit a constant signal and only needs to be read by a reader when near enough. However, battery powered RFID will emit frequencies constantly so that controllers can find what they are looking for without scanning or search just simply looking up. RFID is opt-out technology.