Radio-frequency identification (RFID) is a technology to record the presence of an object using radio signals. It is used for inventory control or timing sporting events. RFID is not a replacement for the barcoding, but a complement for distant reading of codes. The technology is used for automatically identifying a person, a package or an item. To do this, it relies on RFID tags. These are small transponders (combined radio receiver and transmitter) that will transmit identity information over a short distance, when asked. The other piece to make use of RFID tags is an RFID tag reader.

An RFID tag is an object that can be applied to or incorporated into a product, animal, or person 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 tags carry a plain text inscription and a barcode as complements for direct reading and for cases of any failure of radio frequency electronics.

Most RFID tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and de-modulating a radio-frequency (RF) signal, and other specialized functions. The second is an antenna for receiving and transmitting the signal.

There are generally two types of RFID tags: active RFID tags, which contain a battery, and passive RFID tags, which have no batteries
Uses

RFID Technologies systems are used for the following:

•    General transport (logistics), tracking a package, parcel; replacing barcodes
•    Tracking vehicles for road toll
•    Many countries have started using RFID chips in passports
•    Making products harder to falsify; currently proposed for drugs
•    Tags in clothing, e.g. in Jeans
•    Sealing for containers (for the shipping industry). Not required yet.
•    Identifying animals; used for tracking pets, but also for research, for example on turtles.
•    Keys for vehicles. The vehicle key has an RFID tag inside; only the key with the right RFID tag can start the vehicle (this makes copying vehicle keys harder). Also used for locking/unlocking vehicles from a distance.
•    Contact-less identity cards, for example to regulate entry into certain areas; also used for ticketing, or public transport
•    Transponder timing of sporting events.
•    Marking attendance of students

Item-level tagging
Item-level tagging (or RFID item-level tagging, also known as ILT) is the tagging of individual products, as opposed to case-level and pallet-level tagging. Item-level tagging is used to track individual items in order to better control inventory, by providing retailers with the ability to tag individual items on the retail floor. Previously, RFID tags were used to track pallets of merchandise, rather than individual items, through the supply chain. With the use of printed RFID tags, retailers are now able to track inventory at the item level, scan the tag, and know the location.

Retailers are pushing for tagging each individual item. In fact, large companies like Wal-Mart, JC Penney, and Dillard’s are issuing electronic product code mandates, where they request their suppliers to comply with these EPC protocols. In 2005, it was required that the suppliers use RFID tagging at the pallet and case level, but now it is required that they tag on the item-level as well. The reason why is it so important for them to implement this is because they want to avoid losing a sale over an out-of-stock item, which they believe accounts for a big part of their losses. Also, if they know where an item is at all times then it easier to move it to where it is supposed to be. By doing this they reduce transportation costs, they gain added shelf visibility and it drives down wasteful overstock.

Benefits:
Item-level tagging provides a quick, automated, cost efficient and accurate way to track inventory through the supply chain and in the retail environment. Benefits to item-level tagging include better visibility and control of inventory and an expansion of customer experience capabilities. Item-level tagging is critical in order to determine how much inventory is on the floor, what sizes and colors need to be restocked and what inventory is available in stock rooms. Other benefits include the ability to keep a fully stocked floor, increased time and labor savings, increase inventory accuracy, and reduction in clearance items due to incorrect inventory and excess ordering.
Industries Using Item-Level Tagging

•    Apparel
•    Consumer goods
•    Electronic goods

Mobile RFID
Mobile RFID (M-RFID) can be defined as services that provide information on objects equipped with an RFID tag over a telecommunication network. The reader or interrogator can be installed in a mobile device such as a mobile phone or PDA.

Unlike ordinary fixed RFID, mobile RFID readers are mobile and the tags fixed, instead of the other way around. The advantages of M-RFID over RFID include the absence of wires to fixed readers and the ability of a small number of mobile readers can cover a large area, instead of dozens of fixed readers.

The main focus is on supporting supply chain management. But this application has also found its way in m-commerce.[citation needed] The customer in the supermarket can scan the Electronic Product Code from the tag and connects via the internet to get more information.

ISO/IEC 29143 "Information technology — Automatic Identification and Data Capture Technique — Air Interface specification for Mobile RFID interrogator is the first standard to be developed for Mobile RFID

Chipless RFID
Chipless RFID tags are RFID tags that do not require a microchip in the transponder.

RFIDs offer longer range and ability to be automated, unlike barcodes that require a human operator for interrogation. The main challenge to their adoption is the cost of RFIDs. The design and fabrication of ASICs needed for RFID are the major component of their cost, so removing ICs altogether can significantly reduce its cost. The major challenges in designing chipless RFID is data encoding and transmission.