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RFID comes in three different types, which are used for different types of item tracking.
Passive RFID – These tags have no power source and can only transmit stored information courtesy of an external electromagnetic field. This is typically applied by means of a reader (also known as an interrogator).
Active RFID – This is a battery powered variant of passive RFID; with these tags the information contained is only transmitted once a reader has been identified as having permission to interrogate the tag.
BAP RFID – Battery assisted passive RFID tags require activation from an external source in order to transmit information about the attached item, but have much greater range. Increased range can be used both for tracking in the wild and for quick stocktaking in a warehouse scenario.
There are many other uses for RFID beyond tracking laptops.
(Image via wikipedia.org)