DisplayOut

Mirrors screen on connected monitor, projector or television

Detects orientation and connectivity

Supports game and video content

Customizable zoom & aspect ratio

iPhone 4S and iPad 2:

Official HDMI adapter (best)
Official VGA cable (better)
Official component cable (good)
Official composite cable (okay)

Supports wireless connection to Apple TV via AirPlay on iOS5+

iPhone 4, iPad and
iPod touch fourth generation:

Official HDMI adapter + iOS4.3 (best)
Official VGA cable (better)
Official component cable (good)
Official composite cable (okay)

iPhone 3GS, iPhone 3G, iPod touch 2nd/3rd generation:

Official component cable (better)
Official composite cable (okay)

As of March 2012, Apple has begun selling updated HDMI adapters that only work with devices that have been updated to iOS 5.1 and later. For best results, please test the cable you have purchased by playing a video in YouTube with the cable connected.