RFID is an acronym for Radio Frequency Identification. RFID is one member in the family of Automatic Identification and Data Capture ( AIDC ) technologies and is a fast and reliable means of identifying just about any material object.

Primarily, the two main components involved in a Radio Frequency Identification system are the Transponder ( tags that are attached to the object ) and the Interrogator (RFID reader). Communication between the RFID reader and tags occurs wirelessly and generally does not require a line of sight between the devices.

An RFID transponder, considered as a next generation barcode, is a miniscule microchip that is attached to an antenna. They come in a wide variety of sizes, shapes, and forms and can be read through most materials with the exception of conductive materials like water and metal, but with modifications and positioning even these can be overcome.

Passive tags are generally smaller, lighter and less expensive than those that are active and can be applied to objects in harsh environments, are maintenance free and will last for years. These transponders are only activated when within the response range of a reader. The RFID reader emits a low-power radio wave field which is used to power up the tag so as to pass on any information that is contained on the chip.

Active tags differ in that they incorporate their own power source, where as the tag is a transmitter rather than a reflector of radio frequency signals which enables a broader range of functionality like programmable and read/write capabilities.

An RFID reader typically contains a module (transmitter and receiver), a control unit and a coupling element (antenna). The reader has three main functions: energizing, demodulating and decoding. In addition, readers can be fitted with an additional interface that converts the radio waves returned from the RFID tag into a form that can then be passed on to another system, like a computer or any programmable logic controller. Anti-Collision algorithms permit the simultaneous reading of large numbers of tagged objects, while ensuring that each tag is read only once.