Before remote keyless entry systems started appearing on American Motors vehicles in 1983, the term key fob was generally used to describe any small decorative token attached to a keychain. They were used to add some bulk or personality to an important possession and chosen so that you could quickly identify your set of keys from others.
Some fobs were also functional, taking the form of bottle openers, flashlights or, another relatively recent addition, USB flash drives.
The term may have originated from watch fobs, according to Webopedia, an online dictionary for words related to computer and Internet technology. Coming from the low German dialect for the word Fuppe, meaning "pocket," watch fobs were around as early as 1888. Others have suggested that the term stands for frequency operated button, but that ignores heavy use of the word before the remote keyless entry system.
By emitting a distinct identity code, remote keyless entry fobs (RKEs) lock or unlock a car's doors with the push of a button. Early systems required a clear line-of-sight and used infrared, but were easily copied. Newer models employ challenge-response authentication over radio frequency and are considered much more secure. As the systems developed, additional functions were added: unlocking or opening the trunk or rear tailgate, starting the car's engine, opening sliding side doors on vans.
Today, the term key fob is most closely associated with the small devices used to gain entry into apartment buildings or commercial offices. Hold the fob up to a reader pad, known as an interrogator, or other device it can communicate with and -- voila! -- the door pops open. Most function because of a passive radio-frequency identification (RFID) tag, which allows the exchange of data through electromagnetic waves. Passive tags require no battery source, but require an external field -- here, the interrogator -- to communicate.
A central server, usually located somewhere in the building, connects with the interrogator/s and can be programmed to allow or disallow access to certain areas or within certain time frames.
Easy and cheap to install and maintain, RFID systems have been used to do a lot more than keep unwanted visitors from buildings. The Zipcar services uses RFID cards. RFID tags are used for traffic management and toll collection. Wal-mart demands that RFID tags be placed on all shipments to improve supply chain management and to track product movement. And the tag inside of your fob is basically the same as that implanted inside of your pet cat to allow for tracking and identification. As early as 1998, tags were similarly implanted in humans. Professor of cybernetics Kevin Warwick had a chip put into his arm so that, with the wave of his hand, he could turn on lights, adjust the heat in his home and open doors. The tool once used to help you remember your keys may make them completely obsolete.