RFID Tags (RFID Transponders) are classified into three types based on the power source to RFID tags:
1) Active RFID Tags,
2) Passive RFID Tags,
3) Semi-Passive RFID Tags

Active RFID Tags

Active RFID tags refer to RFID tags which have their own power source, so they can receive a weaker signal from the RFID interrogator/reader, and the power source on the tag boosts the return signal. These types can have ranges of many tens of meters and even hundreds of meters, but cost more because of their size and sophistication. Battery life can also limit the life of the active RFID tag.

Passive RFID Tags

Passive RFID tags refer to RFID tags which are powered solely by the RFID interrogator/reader. The interrogator emits a radio frequency (RF), which powers the silicon chip on the tag when it is within range of the RF field. When the power to the silicon chip on the tag meets the minimum voltage threshold it require to turn on, the silicon chip can then send back information on the same RF wave. Range is usually limited to several meters.

Semi-Passive RFID Tags

Semi-Passive RFID tags refer to tags with a power source (usually a laminar, flexible, low cost battery) which can be used for on tag sensing (e.g. temperature), but not to boost range.