Past
HTML5 is a markup language for structuring and presenting content on the Internet. It is the fifth revision of the HTML standard, and includes CSS3 and a series of JavaScript APIs.
Although HTML5 has been well known among web developers for years, it became the topic of mainstream media around April 2010 after Apple Inc’s then-CEO Steve Jobs issued a public letter titled “Thoughts on Flash” where he concludes that “Flash is no longer necessary to watch video or consume any kind of web content” and that “new open standards created in the mobile era, such as HTML5, will win”.
Current
From there, we seen lot of attention given to HTML 5; and considering success of mobility as platform The focus of the mobile world is turning to HTML5.
Apple is promoting HTML 5, Microsoft is also promoting HTML 5 and development for it;s upcoming OS Windows 8 can be done in HTML 5. There is large amount of material available from Microsoft to develop Windows 8 application using HTML 5. Major versions of browsers such as Internet Explorer, Firefox, Chrome, Safari, and Opera implement HTML5 to a large degree and working hard to make it 100% compatible with HTML 5.
Even Adobe also realised importance of HTML 5 and Adobe has released a first version of a Flash-to-HTML5 conversion tool for existing flash content; although not fully working!
Developer community (specially mobile) is also in favour of HTML 5 considering it’s ability to create cross platform applications, which is major topic of debate 
Mozilla currently creating it’s one mobile OS like Android under name ‘Boot to Gecko’.
http://www.mozilla.org/en-US/b2g/
Interestingly it will also use HTML 5 to develop mobile application. Using HTML5 and the new Mozilla-proposed standard APIs, developers everywhere will be able to create amazing experiences and apps. Developers will no longer need to learn and develop against platform-specific native APIs.
Right now, HTML5 is positioning itself to be the No. 3 mobile platform behind Apple’s iOS and Google’s Android, the two most widely-used native app platforms.
Lot of open-source API’s, range of HTML 5 books makes HTML 5 more easy to learn an adopt.
Google is pushing HTML5 hard, not surprising since the greater impact that web pages and apps have, the more advertising it can sell.
Many of Google’s famous front page doodles, like this Jules Verne-inspired interactive submarine, are built using HTML5.
Future
Google and Microsoft have set aside their differences to join in sponsoring a conference dedicated to HTML5, the emerging open standard for Web applications.
According to a recent study by financial researchers Bernstein Research, HTML5’s web-based apps are more cost-effective and less labour-intensive than building different native apps for iOS, Android and Windows Phone.
Considering all this, we can surely say HTML 5 holds really good future; specially in mobile domain!
One Billion HTML5 Phones to be Sold Worldwide in 2013
Long leave HTML 5
