The iPad, along with the iPhone and iPod Touch, does not support Adobe Flash. This include Flash videos, games and websites that use Flash for navigation. As time goes on, more developers are turning to HTML 5 to do the things they used to do with Adobe Flash, with HTML 5 being fully supported by the iPad's Safari browser.
But why doesn't Apple just simply support Flash until HTML 5 catches up?
Flash lacks reliability.
Flash has been pointed to as one of the most common culprits when a Mac crashes, which is one of the major reasons why Steve Jobs took a stand against Flash coming to the iOS platform. Flash also raises security concerns and has had performance issues on mobile devices.
Flash eats up the battery.
Apple has always been very sensitive to the battery needs of its mobile devices. When implementing the Retina Display on the newest iPad, they expanded the battery to keep the same basic battery life even though the display required more power. Adobe Flash for mobile devices has issues with eating up a lot of battery power, especially when compared to native apps built from the ground up for the iPad.
Not designed for touch-based screens.
Flash is designed for desktop and laptop PCs, which means it is designed for the same types of input found on these computers: keyboards and mice. As a touch-based device, this would cause a poor user experience for iPad users trying to use a Flash-based website or play a Flash game.
Adobe is dropping mobile support of Flash.
Perhaps the biggest reason why we won't see Flash in the future comes not from Apple, but from Adobe. Flash has continued to have problems in the mobile market, and with the rise of HTML 5, the writing is on the wall. Adobe dropped support for mobile Flash and switched their support to HTML 5 in 2011.