Radio-frequency identification (RFID) is a technology that incorporates the wireless use of electromagnetic fields or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to transfer data for the purposes of uniquely identifying and tracking tags attached to various objects. RFID is coming into increasing use in industry as an alternative to the bar code, as it does not require direct contact or line-of-sight for scanning.

An RFID system consists of three components: an antenna, a transceiver and a transponder (the tag). The antenna uses radio frequency waves to transmit a signal that activates the transponder. Once the tag is activated it transmits data back to the antenna. This transmitted data is used to notify a programmable logic controller that an action should occur. The action can be as simple as raising an access gate or as complex as interfacing with a database to accomplish a monetary transaction.

Low-frequency RFID systems (30 KHz to 500 KHz) have short transmission ranges that is usually less than six feet. High-frequency RFID systems (850 MHz to 950 MHz) offer longer transmission ranges that is more than 90 feet. The higher the frequency of RFID, the more expensive the system.