HTML5 video
In 2010, in the wake of Apple iPad launch and after Steve Jobs announced that Apple mobile devices would not support Flash, a number of high-profile sites began to serve H.264 HTML5 video instead of Adobe Flash for user-agents identifying as iPad. HTML5 video was not as widespread as Flash videos, though there were rollouts of experimental HTML5-based video players from DailyMotion (using Ogg Theora and Vorbis format), YouTube (using the H.264 and WebM formats), and Vimeo (using the H.264 format).
HTML5 in mobile devices
Offline support helps browsers cache static pages. They depend more on HTTP response headers sent by web servers to fetch HTML, CSS and multimedia required to render the web page. If everything required to render is cached, then a page loads quickly, but even if one item is not cached then everything slows down dramatically.