HTML 5 is still years away from reaching the candidate recommendation stage, but it is already having an effect on the web. In fact, some elements like HTML 5 video and canvas can already be used in modern web browsers like Internet Explorer, Firefox, Chrome and Safari.
With Apple and Google both pushing the standards in order to facilitate more advanced web development, we should see HTML 5 implementations popping up in the next year or two as more companies get on board with the advanced features. This might spell bad news for companies like Adobe, whose popular Flash development platform will see competition from the video and canvas elements.
Here's a summary of some of the new elements in HTML 5:
Video and Audio: New media elements include video and audio, which will allow pages to play video without the need for an external player. These media elements support preload, playback, loop and a control attribute to set the volume.
Canvas: One of the more exciting additions, the canvas element will allow web developers to design and manipulate graphics in a way that is currently only possible with an external plugin like Adobe Flash. One neat example of this is the rendering of the Star Wars opening using the Canvas element.
Data Grid: This one is long overdue. The ability to display data in a grid via HTML 5 will kill off the need for a third-party control or the use of the table element and dynamic HTML to create a grid of data.
Drag and Drop and Increased Interface Control: There are many great interface enhancements coming in HTML 5 including adding methods for drag and drop support. HTML 5 will also add elements like a details element that could allow for an easy implementation for tooltips, though the actual implementation of this element is still not specified. Another example is the revived menu element, which was ditched in HTML 4. This new and improved element will link to a command element to perform tasks.
Enhanced Structure: Of most importance to web designers will be enhancements to the structure of HTML. Building on CSS and div tags, new elements will include header, footer, sectin, nav and article. These will help the browser recognize the parts of the page.
Offline Storage / Database Support: HTML 5 has a lot of great features that will allow for more sophisticated interfaces and better graphics, but don't think data manipulation is being left behind. Support for offline storage, which was originally a part of HTML 5, already exists in most browsers. HTML 5 is also trying to standardized Web SQL databases, which would allow sites to create and manipulate a database on the client computer.
Ug! Who supports what? Want to know which browsers already support which elements? Wikipedia has a comparison of the different browser engines.