Microsoft has given a first look at Windows 8.1, the free update to Windows 8 that it plans to deliver this autumn.

Though it will disappoint some, it should surprise few to learn that Windows 8.1 will not revert all the user interface changes made in Windows 8. Instead, 8.1 will be an incremental update that builds on the Windows 8 interface and its Metro design, but does not replace it.

As such, Windows 8.1 still has the Start screen. It is, however, a more customizable Start screen. There are new tile sizes: a double height tile, to allow apps to show more information, and a smaller tile size, to allow apps to be packed more tightly. There are more options for the Start screen background and colors, including animated backgrounds and the ability to use the same background as used on the desktop. This last change should make the Start screen feel a little less visually disconnected from the desktop world.

The Start screen is also more respectful of personalization. In Windows 8, newly-installed applications just dump their tile or icons on the Start screen. This undermined the personal nature of the screen; you'd have your own, neatly organized apps, but then you'd install a desktop program and it'd just spew a dozen icons all over the place. In Windows 8.1, new apps don't get to automatically stick a tile on the Start screen. They'll still show up in the all programs app view, and they'll be highlighted as new, but the decision to pin them rests with the user.

That all programs view is also more flexible, with a variety of sorting and filtering options. Microsoft says that it will be possible to make "alternate screens" the default when you boot the system. The company mentions explicitly the ability to boot directly to all programs view, rather than the tile view, and it's believed that it will also be possible to boot directly to the desktop.

Not content with putting Start buttons on mice (in addition to keyboards, tablets, and the charms bar), Microsoft is reinstating the taskbar Start button. Clicking it will bring up the Start screen.

Within Metro apps, the button will remain invisible; putting the mouse cursor near the bottom left of the screen will show the button, as it does in Windows 8, but the button itself has changed its appearance. In Windows 8, the button is a miniature thumbnail depiction of the Start screen. In 8.1, it will simply be the Windows logo.

Search is getting reworked to aggregate search results from multiple content sources, including files, apps, settings, and the Web, simultaneously.

Some of Windows 8's obvious limitations are being lifted. In 8.1, Metro apps can be run on multiple monitors simultaneously. On any single monitor, more than two applications can be run simultaneously. Instead of Windows 8's fixed split, where one application gets 320 pixels and the other application gets the rest, the division between apps will be variable. It'll also be possible to have multiple windows from a single app so that, for example, two browser windows can be opened side-by-side.

The built-in applications will get a bunch of updates, and some new apps will be added. Microsoft gave a little information about what we can expect to see—fewer restrictions on the Photos app so it can open files from more places and perform light editing, a "completely redesigned" Music app to make it easier to play your own music (and, we hope, have less of the hard sell that the current app has), and built-in saving directly to and loading from SkyDrive, even when offline. The company says that it'll provide more information on the new and updated apps later in the year.

Work is also being done on two of the "special" built-in apps: Settings and Internet Explorer. A major flaw with using Windows 8, especially on a tablet, is that many, many settings can only be found in the desktop Control Panel, forcing finger-based users onto a mouse-based interface. Microsoft claims that in 8.1, the Settings app will contain "all" of the settings on your device, including things like joining domains and changing the screen resolution.

Internet Explorer 11 will, of course, be faster, have better standards support, and include all the other things we expect new browsers to do. One of those features—not yet confirmed, but strongly hinted—is support for WebGL 3D graphics. The browser will also catch up to Chrome and Firefox in other regards, with tab sync across machines.

Overall, these sound like sensible changes. The new operating system will keep the same core elements as Windows 8 but assemble them in a way that's more flexible, more personal, and fundamentally more useful. A beta of the new version will become available on June 26, coinciding with Microsoft's developer conference, BUILD.