Windows 10 For Mobile

Windows 10 Mobile is the latest often-changing name of Microsoft's phone and tablet operating system, and it's not coming alone, as we learned at Build 2015.

Formerly known as Windows Phone 10 and then Windows 10 for phones, it's bringing some friends (though, some would call them rivals), with Android and iOS app compatibility.

There's going to be an easy way for developers to port over their existing code, and that means more apps running on Windows 10 Mobile devices.

That bodes well for Microsoft's goal of having Windows 10 on one billion devicesin two to three years. Also a big help to increasing its Lumia phone sales is the free Windows 10 download for all W8.1 devices.

Every device running Windows Phone 8.1 right now will be updated to Windows 10 in time. According to Microsoft at its MWC 2015 press conference, it will be updating all the devices it can to the new platform and hopes to have it done by the end of the year.

After months of rumors and speculation Windows 10 Mobile has been officially unveiled by Microsoft. Forget Windows Phone 9, in fact forget Windows Phone altogether, because this is supposed to be Windows... on a phone.

This first build is simply a technical preview of Windows 10 Mobile, and as such contains just a sampling of the features we're expecting to eventually see.

As an unfinished build, this Windows 10 Mobile technical preview is liable to be unstable, and Microsoft recommends caution when installing it - maybe on a secondary Windows Phone device rather than your main phone.

To get started, download the Windows Insider app from Microsoft's digital storefront. Oh, and only users with the Lumia 630, Lumia 635, Lumia 636, Lumia 638, Lumia 730 or Lumia 830 will be able to install it for now.

Cut to the chase

What is it? The next major upgrade for Windows Phone
When is it out? Later in 2015
What will it cost? Nothing, it's a free download

Windows 10 Mobile release date

Windows 10 will ship for desktops later in 2015 and there's every chance that the phone version will arrive at around the same time. Unfortunately Microsoft isn't getting any more specific than that at the moment.

Windows 10 Mobile has begun seeding to selected testers now to help developers get their heads around the new platform.