Read this tutorial to learn what are iPad supported.

iPad Supported Video Formats

H.264 video (up to 720p, 30 frames per second; main profile level 3.1 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats)

MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats.

Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format .

iPad Supported Audio Formats

AAC (16 to 320 Kbps); protected AAC (from iTunes Store)

MP3 (16 to 320 Kbps), MP3 VBR

Audible (formats 2, 3, and 4)

Apple Lossless

AIFF; WAV

iPad Supported TV Formats

Support for 1024 by 768 pixels with Dock Connector to VGA Adapter;

576p and 480p with Apple Component AV Cable;

576i and 480i with Apple Composite AV Cable.

iPad Supported eBook Formats

ePub - This open iPad eBook format is used by many online stores. You can also convert other formats to ePub and then sync them to the iPad via iTunes.

PDF - PDF is the reigning downloading document format on the website, so you're likely to find ebooks in this format. The iPad lets you transfer PDF to iPad and read them via third-party apps.

iBooks - The books purchased through the iBooks Store are actually in ePub format, but include DRM to prevent unauthorized sharing or copying.

Kindle - Amazon's Kindle isn't just an ereader that competes with the iPad, it's also an ebook format. Though you can't read Kindle books through the iBooks apps, you can read them on the iPad using Amazon's Kindle app.

Barnes & Noble - Just like with Amazon, Barnes & Noble has an app that lets you buy read books purchased from their online store on the iPad.