Analysis: Dave Lee, BBC North America Technology reporter, San Francisco

This time last year, Nadella was preparing for a massive launch - Windows 10. For the first time the operating system is free. The goal - to get it on as many devices as possible, because then the fun can begin.

Over 270 million units later, Windows 10, it's time to see what he can do. In 2016 release, the excitement around the AI and AR.

AI - Artificial Intelligence - is only-slightly-jokey reputation as a technology that could potentially lead to the end of humanity as we know it. But this is not "man versus machine", Mr Nadella said, but "the man with the machine."

He said that the bots new applications, as well as demonstrate the assistant Cortana Microsoft's flash - it is integrated into other programs such as Skype. The goal here is to have the ever-present assistant, which grows more intelligent over time.

AR - Augmented Reality - is now ready for developers. First HoloLens Headsets to be sent out, and with it the promise of calculating the events that we had never imagined for education, business and entertainment.

But I must say that the on-screen demo HoloLens are fantastic compared to the fact that the device can actually do today.

How to be run on Windows 10, people asked if Microsoft can drag themselves back into relevance.

Tonight's show AI and AR proves that they were superior. Microsoft is exciting again.