Microsoft unveils Windows 8 to the world today, a reimagined Windows for the next-generation of devices and hardware.

The new Start Screen and immersive Metro experience are designed to make experiences in Windows 8 “totally personal,” according to Microsoft’s director of Windows experience, Jensen Harris. “We’ve tried to eliminate and reduce modes in the UI,” he said during a special preview event of Windows 8 on Monday. Harris detailed a number of new features to the Windows 8 interface that will allow developers and apps to share content and screens with each other. Microsoft is including a semantic zoom feature in the Start Screen to allow users to zoom right out of the experience and see the whole Start Screen in one page, a useful option for those with a large number of tiles. The software maker has planned this unique interface very well, considering a number of scenarios and ways that end users will interact with it.

The sidebar of the Start Screen experience includes five charms. The charms allow users to access search, share, start button, devices and settings. The charms also include an at a glance look at the network status and power status of a device. Harris describes the experience as “fast and fluid” for end users. At the heart of the entire experience is Microsoft’s web browser. “The most important app we build is Internet Explorer,” admitted Harris as he explained how Internet Explorer 10 in Windows 8 includes more hardware acceleration, sharper text and is fully multi touch enabled. A swipe from the bottom of Microsoft’s immersive browser experience reveals the address bar and frequently visited and pinned sites. The browser experience is natural, fast and easy to use.

Microsoft’s search experience in Windows 8 allows app developers to take advantage of the powerful search features baked straight into the new operating system. App developers can use a “search contract” to allow Windows 8 to search within their application natively from the search experience. The user interface allows end users to simply search for a particular phrase and flick through apps to see results. Similarly, a “picking contract” will allow app developers to share their data across the operating system. Harris demonstrated this by picking to share multiple photos from different applications whilst inside the tweet@rama Twitter demo app. The idea of apps working alongside each other is one that Microsoft wants to drive home. “We have a point of view that apps should be able to work together,” says Harris.

If you thought Windows 8 was all touch then you’re wrong. Microsoft is focused on supporting traditional computing methods just the same way as touch. All the features of the Start Screen can be activated using a mouse and keyboard. Right clicking inside the interface brings up the context menu (activated by swiping from the bottom of the screen in the touch world). Microsoft is also building in stronger pen support in Windows 8. “We were innovations in pen,” says Harris before admitting that the trend hasn’t caught on in recent years. “Windows has great pen support” he adds. Microsoft’s recognition API allows handwriting to be recognised throughout apps without the app developer needing to code additional support for it.

Microsoft’s Metro apps extend to the Windows Live platform too. The company is creating Metro style apps for mail, photos, calendar and people. The apps are identical to Windows Phone and include similar features such as threaded messaging and integrated contact points into a single individual. The apps aren’t available in the Windows 8 developer preview but Microsoft demonstrated them on Monday. Think Windows Phone people hub and messaging and they are almost identical. The applications all run on a new platform that allows developers to leverage a new set of Windows Runtime APIs (WinRT). Developers can create Metro applications using C++, C, C#, VB, HTML/CSS and JavaScript. “We want to make sure developers can bring their experience and knowledge to building these applications,” said distinguished Windows engineer Ales Holececk. ”We are putting XAML, HTML and CSS at an equal footing,” he explained. Microsoft is encouraging developers to focus on Metro applications instead of traditional desktop apps that use win32, .NET and Silverlight. The ARM based version of Windows 8 will not support the traditional desktop apps so it’s a big play to shift developers onto a rethought application platform.

Overall, Microsoft’s new user interface is a risky product bet, but one that feels right considering its other product lines. The interface borrows a large amount from its Windows Phone cousin but creates its own use of live tiles and Metro applications. It’s a fresh start to Windows and if it’s coupled with the appropriate hardware then it will do well to penetrate certain markets. It’s a joy to use and immediately creates a very personal experience in the same way that no Windows Phones are alike. The question remains over applications but Microsoft has a loyal development community and a following that will be excited about the company’s announcements this week at BUILD. The message is clear, developers – fire up your copy of visual studio and go create.