CEC (Consumer Electronics Control) is an HDMI (High Definition Multimedia Interface) feature found on many TVs and peripherals. Basically, CEC makes your devices work better together. However, it is often turned off in your TV's default settings.
HDMI-CEC by Another Name
Unfortunately, you often won't see the acronym HDMI-CEC when looking at your TV's or peripheral's specifications list. Instead, be aware that manufacturers like to "disguise" their HDMI-CEC option under a branded trade name.
The Usefulness of HDMI-CEC on Your TV
HDMI-CEC enables your TV-connected devices to have control over your TV and vice versa. For example, you can control your disc player through your TV remote, or enable your TV to automatically switch to your game console's input when you press the game console's controller to turn it on.
HDMI-CEC is a very useful option and well worth the small amount of trouble it may take for you to find and enable it. However, once you have it set up, it will save you the time and hassle of switching between inputs.