A key fob is a decorative item which many people carry with their keys, on a ring or a chain, often to provide a better grip or to simply make a personal statement. There is essentially no limit to the forms of key fobs available. Simple shapes of smooth metal or plastic, often with a message or symbol, are the most common. A fob may be the shape of a symbol or a small representation of an object, or it may be functional itself; a small flashlight, calculator, penknife, bottle opener or USB flash drive are common examples. See keychain for a more extensive list of such items.
Electronic key fobs are used for remote keyless systems on motor vehicles. Early electric key fobs operated using infrared, so they needed a clear line of sight, and could be copied using a programmable remote control. More recent models use challenge-response authentication over radio frequency, so these are harder to copy and do not need line of sight to operate.
