3 Mirror Your Screen
Your Apple TV can also let you use your TV as a second screen or a way to share your screen with other people. You can use AirPlay from your iPhone or iPad to share your current music or movie; or, you can mirror your entire display.
There are even some games and third party apps that format to your TV using AirPlay and then let you use your iOS device as a secondary input (such as a game controller).
If you have a Mac, you can use AirPlay to either mirror your screen or use your TV as a second screen. If you want to browse the Web on your Apple TV using your iPhone, you could always just mirror Safari. Or, you can download apps like AirBrowser or AirWeb to use a browser formatted to your TV.