Well, it's a lot more than HTML language - it is the synchronization of ALL desktop and mobile browsers!

In common tongue: one STANDARD to rule them all! :)

The history of HTML in few lines:
1989. - HTML
1994. - HTML2
1995. - HTML3
1997. - HTML4
2012. - HTML5 ?

The goal of HTML is to create standard and consistent web expirience (browsing) across all devices and browsers. Whateaver you are on desktop computer, notebook, tablet, mobile phone, regardles what browser does your devices is using - EXPERIENCE is the same!

"HTML5 is still being developed, and as of early 2012 isn't 100% finalized, but the browsers (Google Chrome, Mozilla FireFox, Microsoft Internet Explorer, Apple Safari, Netscape Navigator) are starting to implement some of its features, and together they are working hard to get HTML5 full ready for someday in the future."