CEC

Consumer Electronics Control (CEC) is a feature of HDMI designed to allow users to command and control devices connected through HDMI[1][2] by using only one remote control. – Wikipedia

For example, you can control your Raspberry Pi media center with the remote of your TV through HDMI.

Vendor	Trade name
AOC	E-Link
Emerson Funai Magnavox Sylvania	Fun-Link
Hitachi	HDMI-CEC
Insignia	INlink
ITT	T-Link
LG	SimpLink
Mitsubishi	NetCommand for HDMI, Realink for HDMI
Onkyo	RIHD (Remote Interactive over HDMI)
Panasonic	HDAVI Control, EZ-Sync, VIERA Link
Philips	EasyLink, Fun-Link
Pioneer	Kuro Link
Runco International	Runco Link
Samsung	Anynet+
Sharp	Aquos Link
Sony	BRAVIA Link, BRAVIA Sync, Control for HDMI
Toshiba	CE-Link, Regza Link
Vizio	CEC

CEC

Terms from various vendors