All we expected from Microsoft’s Windows 10 event was a preview of some new features coming in the next version of Windows and Windows Phone and maybe the next version of Office. In a presentation that lasted for more than two hours, Microsoft surpassed those expectations wildly. Not only did it announce a fundamental shift in the firm’s pricing strategy for Windows, it showed off a futuristic holographic computing experience called HoloLens.

Windows 10, expected on the market this autumn, will be available for one year as a free upgrade to users of Windows 7, Windows 8.1 and Windows Phone 8.1, announced Terry Myerson, who runs Microsoft's operating systems group. This is a marked change for Microsoft, which has charged for new versions of Windows, one of its main profit drivers.

The new 'free' strategy is aimed at establishing Windows on as many devices as possible, and then trying to make up for lost revenue by selling valuable services such as Office over the internet, or cloud.

"It's a necessary evil as CEO Satya Nadella and Microsoft have recognized the 'golden goose' and major revenue opportunities will happen after the upgrades have taken place" Daniel Ives, an analyst at FBR Capital Markets, told Reuters. "Microsoft needs to lay seeds for its cloud-centric strategy and Windows 10 is the epicenter of that strategy. It's all about making it attractive for the ecosystem to upgrade onto this next-generation platform."

The move is a recognition that, in the last decade, Windows, featured on roughly 15% of computing devices including phones and tablets, has become largely irrelevant for many consumers. Microsoft hopes that by making the software free, it will attract the more than 1 billion personal computer users of Windows to run it on other devices.

Microsoft’s second major announcement was a device called the HoloLens, which looks like a wireless visor. It ups the stakes in the emerging market for virtual reality, being targeted by Facebook’s Oculus.