RFID (Radio Frequency Identification Device) refers to systems that allow a device to read information contained in a wireless device that is commonly called a tag, & provides a method to transmit & receive data from one point to another.  RFID is coming into increasing use in industry as an alternative to the bar-code.  The advantage of RFID is that it does not require direct contact or line-of-sight scanning.  An RFID system consist of 3 components: an antenna & transceiver (often combined into 1 reader) & a transponder (the tag).  The antenna uses radio frequency waves to transmit a signal that activates the transponder.  When activated, the tag transmits data back to the antenna.  Low-frequency RFID systems (30KHz to 500KHz) have short transmission ranges (generally less than 6 feet).  High-frequency RFID systems (850MHz to 950MHz & 2.4GHz to 2.5GHz) offer longer transmission ranges (more than 90 feet).  In general, the higher the frequency, the more expensive the system.

RFID is sometimes called Dedicated Short Range Communication (DSRC).