The Windows 10 Fall Creators Update (FCU) is starting its roll out, for 'desktops' and 'Mixed Reality headsets' at least, according to Microsoft. Officially, it's Windows 10 branch 1709 and also officially coming to Windows 10 phones such as the Lumia 950 and Alcatel IDOL 4 Pro. The desktop rollout will take several months and the final push to production phones normally happens around a month 'in', though note that the 'Release Preview' build for phone Insiders is now available. We'll keep you posted on production pushes.

On the phone, the FCU basically means better security, better enterprise features, and a reset of the two year support deadline, forward to Autumn 2019.

From Microsoft:

From the initial launch of Windows 10, we’ve been on a mission to empower the creator in all of us. We believe in the fundamental human need to create to propel the world forward.

Today, we deliver the Windows 10 Fall Creators Update offering breakthroughs in creativity – from bringing mixed reality and 3D to the masses, to faster broadcasting for gaming, to turning photos and videos into real memories, and so much more. The Windows 10 Fall Creators Update can be experienced on a wide variety of Windows 10 PCs and on a range of Windows Mixed Reality headsets available for the first time today.

We believe the PC is the ultimate canvas for creativity and can empower people to create like never before. This is why we are building Surface to be the ultimate laptop and are delighted to introduce the Surface Book 2, the most powerful Surface yet.

The Windows 10 Fall Creators Update is packed with new innovations including, new Inking experiences like inking directly on PDFs, a new Find my Pen feature, Continue on your PC with Cortana or your phone’s browser including, Microsoft Edge for seamless Windows experiences across devices, enhanced security and privacy features, and improvements in accessibility, including Eye Control. I’m excited about these innovations and in particular four big bets that deliver on our vision for creativity:
Mixed reality for the masses

In short, if you have a touch-enabled Surface desktop or hybrid then there's a lot new, ditto if you're playing with one of the new headsets, so 'Check for updates' in Settings, else just wait and you'll get the latest and greatest in due course.

On a Windows 10 Mobile phone, if it's fully Creators Update/FCU approved then just sit on the Insiders Fast ring and you may well already be running the Release Candidate. Update: FCU, the same build as the RC, is now available on the Release Preview ring too. So essentially any Insider ring will do at the moment.

The launch of the Surface Book 2 was interesting, and it's now in two sizes, see the promo launch video below: