Passive RFID tags are by far the most common. They do not contain any power and receive this from the RFID reader. This is sufficient to power any device in the RFID tag and reply with the required data.

The so called RFID smart tags, or RFID smart labels are all passive.

Some of the advantages and disadvantages of passive RFID tags are tabulated below:

Advantages Passive RFID tags:
* A RFID passive tag by definition does not have a battery and their life is almost indefinite.
* Passive RFID tags are simpler to manufacture than active RFID tags and therefore cost considerably less.
* As passive RFID tags are generally simpler, and they do not contain a battery they can be made much smaller than active ones.

Disadvantages Passive RFID tags:
* The range of passive RFID tags is limited - typically a metre or so.
* As power in RFID passive tags is very limited, sensors are rarely fitted as these will require additional battery power.
* The fact that the tag is passive means that it remains operable for possibly years after it was initially used - this can have personal privacy implications unless it is deactivated.