What is HTML5?
It's one of the latest catch phrases aroudn these days, almost everybody who's even a little web savvy has heard the term "HTML5". This is the next evolution of HTML(Hyper Text Markup Language), which is the client-side code that's used by just about every website our there. The last iteration of the language was HTML4 who's debut was back in 1997.
Why is it such a big deal?
HTML 4 has been tweaked, stretched and augmented beyond its initial scope to bring high levels of interactivity and multimedia to Web sites. Plugins like Flash, Silverlight and Java have added media integration to the Web, but not without some cost. In search of a "better user experience" and battery life, Apple has simply dropped support for some of these plugins entirely on mobile devices, leaving much of the media-heavy Internet inaccessible on iPads and iPhones. HTML5 adds many new features, and streamlines functionality in order to render these processor-intensive add-ons unnecessary for many common functions.
Assuming content providers sign on (and many are), this means you won't have to worry about installing yet another plugin just to listen to a song embedded in a blog or watch a video on YouTube. Similarly, this is a big deal for platforms that either don't support Flash (e.g., iPhone and iPad), or have well documented problems with it (e.g., Linux). It will be a particular boon to those smartphones for which supporting Flash has proven problematic.
So what exactly can it do?
HTML5's most touted features are media playback and offline storage. With HTML4, sites usually have to reach for Flash (or Silverlight) to simply show a video or play music. HTML5 lets sites directly embed media with the simple HTML tags." and "" -- no plugins required. There are some issues currently being debated by the powers that be, and a particularly sticky one deals with file format. Some companies, especially Mozilla, are pushing for the adoption of the open-source Ogg format, which is free for anyone to use. Others, like Apple, would prefer the higher quality H.264 format, which will eventually require browser makers to pay licensing fees to support it.
The other major addition that has garnered media attention is the ability to store offline data for Web apps. One of the major roadblocks in the march to replace traditional desktop apps has been that the Web-based ones are useless without an Internet connection. Google developed a stopgap solution with Gears, but that product has been retired as the company is shifting its focus to HTML5. This will mean being able to create files in Google Docs or draft e-mails when away from an Internet connection. These changes would be automatically synced the next time you're online.
HTML5 also adds new interactivity features, like drag-and-drop, that have already found their way into Gmail.
When can I start using this?
You're probably already using it now without knowing. The latest versions of safari, Google Chrome and Firefox all support at least some elements of HTML5. And the latest upcoming browser from Microsoft, IE9 will support it too. It's being used by facebook, gmail and youtube, and many other huge websites out there.