The term remote keyless system (RKS), also called keyless entry or remote central locking, refers to a lock that uses an electronic remote control as a key which is activated by a handheld device or automatically by proximity.  Widely used in automobiles, an RKS performs the functions of a standard car key without physical contact. When within a few yards of the car, pressing a button on the remote can lock or unlock the doors, and may perform other functions. A remote keyless system can include both a remote keyless entry system (RKE), which unlocks the doors, and a remote keyless ignition system (RKI), which starts the engine.