Radio-frequency identification (RFID) is the use of tags applied to things for the purpose of identification and tracking using radio waves. Some tags can be read from several meters away and beyond the line of sight of the reader.

Most RFID tags contain at least two parts, integrate circuit and antenna. Integrated circuit is used for storing and processing information, modulating and demodulating a radio-frequency (RF) signal, and other specialized functions. Antenna is used for receiving and transmitting the signal.

There are two types of RFID tags: active RFID tags and passive RFID tags. Active RFID contains a battery and can transmit signals autonomously. Passive RFID tags have no battery and requires an external source to provoke signal transmission.

RFID is used in enterprise supply chain management to improve the efficiency of inventory tracking and management. RFID is becoming increasingly prevalent as the price of the technology decreases. RFID can be used in a variety of applications such as:

* Access management
* Tracking of goods and RFID in retail
* Tracking of persons and animals
* Toll collection and contactless payment
* Machine readable travel documents
* Smart dust (for massively distributed sensor networks)
* Location-based services
* Tracking Sports memorabilia to verify authenicity

RFID tags are often a replacement for UPC or EAN barcodes, having a number of important advantages over the older barcode technology. They may not ever completely replace barcodes, due in part to their higher cost and the advantage of multiple data sources on the same object.

The unique identity is a mandatory requirement for RFID tags. RFID tag data capacity is large enough that each individual tag will have a unique code, while current bar codes are limited to a single type code for a particular product. The uniqueness of RFID tags means that a product may be tracked as it moves from location to location, finally ending up in the consumer's hands.

A primary RFID security concern is the illicit tracking of RFID tags. Tags which are world-readable pose a risk to both personal location privacy and corporate/military security.