Adobe Flash Player
Steve Jobs also claimed that a large percentage of the video on the Internet is supported on iOS, since many popular video sharing websites such as YouTube have published video content in an HTML5 compatible format, enabling videos to playback in mobile web browsers even without Flash Player.
HTML5 in mobile devices
Microdata, 3D animation rendering, FileReader API, IndexedDB, and local device support or the WebWorkers feature respectively are the top five HTML5 features not supported across the top 15 mobile devices in all USA, UK, Germany, Malaysia, Australia markets examined.