Everything that Microsoft announced at its Windows 10 event in four handy bullet points

In an event, which ran for more than two and a half hours, and which we stayed up half the night to watch -- darn those time zones -- Microsoft dropped a boatload of information that we have just about wrapped our heads around. Here's a primer.

Sure, we knew that Microsoft's Windows 10 announcement would be big. We expected the company to show us a peek of new features in the latest version of its operating system coming later this year, a touch-friendly version of Office and maybe how Windows 10 would look and feel on smartphones. Not only did Microsoft meet our expectations -- it blew past them.

In an event, which ran for more than two and a half hours, and which we stayed up half the night to watch -- darn those time zones -- Microsoft dropped a boatload of information that we have just about wrapped our heads around. Here's a primer.

- Windows 10 will be free. Yes, really.

As long as you're on Windows 7, Windows 8.1 or on Windows Phone 8.1, you're eligible for a free upgrade to Windows 10. The only catch is that you'll need to upgrade your system any time within a year of the commercial release of Windows 10, There was some confusion about whether users would need to pay Microsoft after a year -- Microsoft had some confusing language about treating 'Windows as a service,' something that they currently say about Office 365, which users 'subscribe' to -- but really, it's all good. As long as you upgrade to Windows 10 within a year of its release, Microsoft will continue pushing updates to your system to make sure you're on the latest version. Always.

- Windows 10 fixes everything that was wrong with Windows 8 -- and then some.

Windows 8 was a Frankenstein OS that stitched two disparate users interfaces -- one meant for touchscreens, the other for keyboard and mouse -- together and tried to pass it off as the Holy Grail for next-generation computing. Users didn't bite.

With Windows 10, Microsoft has refined this dual experience to make Windows palatable on both regular, non-touch hardware and tablets. They call it 'Continuum'. What happens is this: on hybrid devices with detachable keyboards that double up as tablets, Windows will automatically tailor the user interface to how you're using the system. If you have a keyboard, you'll get the regular Start menu. If you're on a tablet, youll get a full-screen Start menu, similar to the current one in Windows 8.1.

There are a host of new improvements: a single Settings panel to change stuff across the system, not the weird, two-headed Control Panel and Settings Pane in Windows 8.1; a brand new browser that might replace Internet Explorer (we don't know for sure yet); and the ability to stream Xbox games directly from your Xbox One to your phone, tablet or desktop.

- Windows Phone is far from dead.

This event was as much about Windows Phonne getting a new lease of life rather than being designated to the dustbin of failed Microsoft products like Zune. In an important step, Microsoft is combining the underlying code of Windows and Windows Phone -- it's all Windows 10 now, baby! -- to make it easier for developers to write one app that runs across all Windows devices. This is a big deal, because lack of apps is one of the main reasons holding back Windows Phone right now. And yes, it will be called just 'Windows', not 'Windows Phone.'

And oh, a brand new, touch-friendly version of Office will be included for free on all Windows devices under 8 inches in size.

- Yes, the Microsoft Holographic headset is very real (and round the corner).

Microsoft showed off something called the HoloLens, a holographic headset that looked wildly futuristic. It's a hyperrealistic version of augmented reality and it's difficult to capture the experience in words, which is why you should see the video below.

Is it ready for prime time? Not yet. But Microsoft did say that it will be released in time for Windows 10 later this year, which is exciting.