Control Your TV and Sound System
When you set up the Apple TV, it learns about your TV from the HDMI connection and it can control most TVs.
If your sound system is connected to the TV, or through the HDMI connection, then you can even control the sound as well.
It's a handy way to use your Apple TV remote to control everything. When you press the TV button on the remote, it will even switch inputs and get you ready to watch.