The RFID (Radio Frequency IDentification) puts on an object for the purposes of reading the ID (IDentification) and tracking by using radio wave. The RFID can be read from several meters away from the reader.
There are three types of RFID Systems. The First System is the "Active RFID", that uses an internal battery to power their whole circuits, and broadcast radio wave to a reader autonomously. The Second System is the "Passive RFID", that relies entirely on the reader as their power source to reflect signal transmission. The Third System is the "Semi-Passive RFID", that uses an internal battery to power logic circuits.