IE9 left no doubt that Microsoft understood the importance of supporting modern Web standards. But IE10, updated yesterday with the third platform preview, is the vehicle delivering much of that support.

Microsoft fleshed out IE10's impressive list of new technologies at Microsoft's Build conference for developers. New items on the list such as Web Workers, Web Sockets, 3D Transforms, Application Cache, and IndexedDB are music to the ears of many Web developers who want to make rich, interactive Web sites.

But it's important for a much larger developer group, too: IE10 also is a key foundation for Windows 8 applications. That's why Microsoft is boasting of IE10's ability to run "chromeless" in a full-screen mode and a touch-friendly design.

The better the browser's support for new technologies, the better next-gen Windows apps can be. In particular, the apps based on browser technologies will run handily on tablets built with ARM processors, an area Microsoft cares passionately about as it watches millions of iPads fly off Apple store shelves.

Microsoft's Internet Explorer is still dogged by IE6's reputation as slow and lacking support for many Web standards. It was released a decade ago and still is widely used, thanks in large measure to the fact that it's bundled with Windows XP. Microsoft started digging itself out of its browser hole with IE7 and IE8, but IE9 was the real statement that showed the company's competitive juices were really flowing.

IE9 brought support for a lot of browser standards: including HTML5 video and audio, SVG (Scalable Vector Graphics), CSS3 (the new version of Cascading Style Sheets for page formatting), the canvas for 2D drawing. As important, its JavaScript performance leaped, and the browser ignited the current race to build hardware acceleration into the browser for better speed and lower power consumption. And behind the scenes, Microsoft has become active in standards development.

It seems, though, that only so much could be added to IE9. At some point, Microsoft had to call it done--especially given that some standards are still developing.

IE10 fleshes out the standards support. Some modest additions appeared in the first and second platform preview editions--test versions that Microsoft uses to help Web developers ease into supporting the browser and to get feedback.

Supporting the standards

The third platform preview arrived yesterday with a slew of new features, many of them very important to Web apps' look and abilities. On the list of new IE10 standards supported:

 CSS Text Shadow makes it easy to make shadows beneath text, giving something of a 3D look. It's not rocket science, but it adds polish and it's a feature in high demand.

 CSS 3D Transforms can endow objects with perspective to give them a 3D look, for example making it look like a page of an online book is flipping out of the screen as it's turned.

 CSS3 Transitions and Animations can move objects around the screen, rotate them. That makes Web sites and apps more dynamic, in particular in response to user actions such as clicking a button that pops up a dialog box..

 A host of CSS3 abillities including as grid, flexbox, multicolumn, figures, regions, and hyphenation help with making Web page layouts more elaborate and magazine-like. It also helps them adjust to different screen sizes.

 IndexedDB provides a build-in database useful for Web apps that need to store data, notably when they're running when a computer is disconnected from the network. IndexedDB is used, among other technologies, for offline Google Apps access, for example.

 The HTML5 Application Cache (AppCache) feature lets the Web app itself be stored on a computer for offline use.

 Web Sockets, coming back into circulation after a hiatus caused by a security problem, enables high-speed communications between browsers and Web servers. That's good for apps with live data, for example a game that needs to keep multiple players in sync.

 Async scripts lets Web pages break down their programming into chunks that run when they can, no longer holding up critical parts.

 Web Workers let programmers assign parts of a Web app to JavaScript threads that execute in the background, getting out of the way of primary tasks such as running the user interface. They also help take advantage of multicore processors.

 HTML5's Drag-and-Drop interface lets programmers set up Web pages so people can, for example, drag photos to be uploaded onto a live patch of a Web page. Google uses it for accepting Gmail attachments.

 HTML's Files interface lets Web apps manage data stored as a file, for example letting people select a group of files from an operating system's file system or uploading a video divided into multiple separate "blobs" of raw data.

 CSS3 Gradient gives better control over Web objects' colors--a background gradually changing from black to gray, for example--without having to download bulky graphics files.

 SVG Filter Effects let programs process SVG with graphics changes such as lighting effects or blurring.

 The Navigation Timing interface lets programmers precisely monitor events such as Web page loading speeds.

Still missing, unsurprisingly, is WebGL, a low-level interface for 3D graphics that's useful in particular for Web-based video games. That seems like the kind of thing that Microsoft might like with Windows 8 apps, but the company has expressed serious security reservations about WebGL. In addition, Silverlight 5 is getting new 3D abilities, and Silverlight apps can be made into Win8 apps that will run on both Intel and ARM processors, too. Last, it's notable that WebGL uses Khronos Group's OpenGL interface that competes directly with Microsoft's DirectX interfaces.

The third platform preview of Internet Explorer 10 so far is only available as a download with the Windows 8 build issued to developers. That's fine for folks coding up Win8 apps. But those who don't want to mess with an experimental build of an operating system--Web developers spring to mind as one likely group--will have to wait.

Microsoft doubtless will get the new software into more hands eventually--after all, IE10 isn't just for Windows 8. New platform preview versions won't arrive on the earlier eight-week schedule, though, as Microsoft moves to a more relaxed twelve-week cycle.

One big question for Microsoft is whether it will move to a rapid-release cycle the way Google has with Chrome and Mozilla has with Firefox. Right now, it seems unlikely, and Microsoft has promised IE9 support will last until 2020.

That raises the prospect of Web developers faced with a requirement to support today's IE years into the future. That might not sit well, given the power of the Microsoft Windows distribution channel for browsers and the fact that Microsoft's cutting-edge IE10 will look pretty old in a decade.