iOS8 New! The biggest iOS release ever. http://www.apple.com/ios/whats-new/
iOS updates are free. And they’re available to download wirelessly on your iPhone, iPad, or iPod touch the moment they’re released.
Your device even alerts you when it’s time to get the latest version. So you won’t miss out on all the amazing features in new updates.
Update your iPhone, iPad or iPod touch: http://support.apple.com/kb/HT4623
Note: If you’re updating from iOS 4.3.x or earlier, you need to update using iTunes.