RFID tags is a small chip including a tiny antenna and a small-scale integrated circuit. These chips that we will call tags can seamlessly be attached to merchandise, animals or humans without affecting them. What makes the use of an RFID tag even more appealing is its capacity to receive power from a remotely located emitter and hence, there is no need for constantly providing it with power; all is done wirelessly. Furthermore, the size of a tag is application-dependent but is usually less than few centimeters which makes it compliant with any targeted object.
There are many types of RFID tags:
Active RFID tags and Passive RFID tags are fundamentally different technologies that are often evaluated together. While both use radio frequency energy to communicate between a tag and a reader, the method of powering the tags is different. Active RFID tags uses an internal power source (battery) within the tag to continuously power the tag and its RF communication circuitry, whereas Passive RFID tags relies on RF energy transferred from the reader to the tag to power the tag.
RFID Tags come in many shapes and sizes each suited to a specific application. RFID tags also can be read-only (stored data can be read but not changed), read/write (stored data can be altered or rewritten), or a combination, in which some data is permanently stored while other memory is left accessible for later encoding and updates.