Microsoft is moving on from PC and tablets to smartphones.

The company has announced you can now preview its latest operating system on handsets running Windows Phone 8.1, as it has finally released the Windows 10 for phones preview after having already shown what the software can do for PC and tablets. Keep reading to learn more about this initial technical preview and how to get your hands on test builds.

First up...Join Microsoft's Windows "Insider" program.

Although anyone can join via the Insider program's website, Microsoft recommended that only tech-savvy individuals sign up. They must also have access to a phone running Windows Phone 8.1 to install the preview app and get ahold of the test builds. Make sure it's not a daily-use phone, as it'll run a very early preview that might not be super stable.

Microsoft claimed it hasn't bricked a single phone (aka the phone won't turn on in any way) during all of its internal testing, but it warned that such a situation is still possible, so you should be aware that there is some potential risk. There might also be bugs that prevent access to important features like phone dialing or other core functionality.

Note: Instructions on how to join the Insider program and get your phone set up are also on the Insider website.

No. Microsoft has published the following list of supported devices: Lumia 630, Lumia 635, Lumia 636, Lumia 638, Lumia 730, and Lumia 830. They're the only supported phones right now, but Microsoft has promised the company will add new devices, along with new features, over the next few months. You can read more about that here.

You'll likely notice that two flagship devices - the Lumia 1520 and Lumia 930 - are not currently available on the supported device list. No worries. It's just delay due to an upcoming "partition stitching" feature, according to Microsoft, which will allow the company to dynamically adjust the OS space on a device in the future.

Until then, Microsoft said the preview requires smartphones that were "configured by mobile operators with sufficiently sized OS partitions to allow the in-place upgrade, and many of the bigger phones have very tight OS partitions."

A bunch of stuff. You'll get to add full-size background images to Start. There's also more Quick Actions in the Action Center, as well as interactive notifications, enhanced speech-to-text capability, and a more powerful Photos app.

Yes. Microsoft has said there a lot of familiar features in Windows Phone 8.1 that are missing from this current version of the initial technical preview, such as: messaging's dual-SIM support, search, voice note sharing, message drafts, international assisted dialing, Bi-Di language support, spam filter, viewing group recipients, and multiple attachments.

Other missing features include GSM support, reminders, and quiet hours through Cortana. Speaking of Cortana, Microsoft's virtual assistant is only available in the US. The Rooms feature also isn't fully supported. Keep in mind future builds of the preview are expected to bring back many of these features.

And finally, because this is still an early build of the preview, there are several known bugs and things that don’t work right just yet. Existing alarms will not be migrated, for instance, and Wi-Fi settings don't roam. The Photos app may also fail to launch periodically, and trying to set the lock screen picture could fail at times too.

The Cortana tile and settings are also missing on the start screen, among other things.

It's hard to say.

We know that Windows 10 is supposed to overhaul what was available on Windows Phone 8.1. It'll bring universal apps and improved or new versions of apps like photos, calendar, mail, music, camera, messaging, and maps. Maps, for instance, will integrate turn-by-turn directions and basic mapping, making those features available all in one app.

Other improvements include updates to the settings page, an expandable/collapsable notification center, and the ability to act on notifications. You can learn more about what to expect on Windows 10 for phones here.

Check out the video above, or read Microsoft's blog post about the preview.