Consumer Electronics Control (CEC)
Consumer Electronics Control is a feature of HDMI designed to control HDMI connected devices by using only one remote controller; so, individual CEC enabled devices can command and control each other without user intervention, for up to 15 devices. For example, a television set remote controller can also control a set-top box and a DVD player.
It is a one-wire bidirectional serial bus that is based on the CENELEC standard AV.link protocol to perform remote control functions. CEC wiring is mandatory, although implementation of CEC in a product is optional. It was defined in HDMI Specification 1.0 and updated in HDMI 1.2, HDMI 1.2a and HDMI 1.3a (which added timer and audio commands to the bus). USB to CEC adapters exist that allow a computer to control CEC-enabled devices.