This fifth edition was prompted in part by the great increase of computers in industrial controls and automation, which has produced computer programs that can simulate relays and relay contacts. These on/off discrete controls have eliminated the wiring and installation of hardware components in favor of virtual relays and contacts that can be programmed on a keyboard. The devices that perform these operations are called Programmable Logic Controllers (PLCs), or simply programmable controllers. These devices were initially stand-alone computers that controlled a specific robot or manufacturing operation. However, with the advent of the Internet, they have now been integrated with the overall manufacturing process, leading seamlessly to integration with management, sales, procurement, and consumer satisfaction.