RFID

RFID is an acronym for Radio Frequency Identification, a technology traditionally used to keep track of inventory by using data stored in radio reactive transponders. RFID technology has been in existence for a while, and has existed parallel with barcodes in inventory management systems. While barcodes require individual scanning, RFIDs permit inventory to be kept of objects en masse.
The technology that is applied mostly to inventory systems with RFID has been spawning a variety of uses, real and imagined. Cultural commentator Bruce Sterling has been referring to RFIDs as "arfids," in conjunction with an imagined technology of "spimes." Sterling describes spimes as objects that talk to each other using web technologies creating a "web of things." This use of RFIDs in creating a web of things is further explored by Adam Greenfield in his 2006 book, Everywhere: The Dawning Age of Ubiquitous Computing.
Due to current consumer uses of RFIDs expanding into protected and sensitive data such as credit cards, passports, transit cards and ID cards for civic and business purposes, new research into security for RFIDs is being conducted. While most RFIDs are currently unencrypted or poorly secured, some security officials have suggested that wrapping an RFID tag in aluminum will prevent its unauthorized detection and use.
RFID tags on Flickr, with tags
Wikipedia entry for RFID