For die-hard gadget lovers, Microsoft’s Surface event this week was something of a dream come true. The company resurrected its legendary dual-screen Courier concept as the Surface Neo, then it surprised the world by announcing a dual-screen Android phone. The company finally embraced the USB-C port on its new Surface Pro X, Surface Pro 7, and Surface Laptop 3, and it’s even making them slightly upgradable, too.

But if you came wondering about the future of Windows, you might have left a bit confused.

Microsoft did announce a new streamlined version of Windows — dubbed Windows 10X — but it’s only for dual-screen devices like the Surface Neo and with Intel processors inside. You won’t be able to upgrade your PC to Windows 10X, and most of Microsoft’s just-announced devices won’t support it either.

X doesn’t necessarily mark the spot

Heck, the new Surface Pro X tablet doesn’t run Windows 10X, even though they’ve both got that “X” in the name, and you might theoretically prefer a stripped-down Windows to go with its ARM-based chip. The upcoming Surface Duo phone also doesn’t run Windows 10X, even though its dual-screen hardware looks almost exactly like a miniature Surface Neo. (See below.) It’s using Android instead.

While each of these decisions might seem confusing on their face, there may be good reasons behind each one — particularly, if it’s true that Windows 10X isn’t actually a new operating system at all.

Officially, Microsoft hasn’t said anything of the sort — frankly, the company isn’t talking about Windows 10X much at all — but here’s everything we know for sure:

How an early build of Windows 10X works on the Surface Neo, with its intriguing WonderBar that can act as a tiny secondary monitor on demand.

That it’ll ship in late 2020 on similar Intel-powered devices from Asus, Dell, HP, and Lenovo.

That it’ll run “legacy” Win32 desktop apps, not just web apps and Windows Store ones, in a mysterious container tech that preserves battery life.

That the Start Menu is a smartphone-esque launcher now, and Live Tiles appear to be gone.

If we consult years of insider whispers about Microsoft’s alleged internal strategy for Windows, many from The Verge’s own Tom Warren, there’s a simple reason why you shouldn’t care whether Windows 10X ships on just a few devices or thousands. That’s because Windows 10X is likely just a modular shell that gives the core Windows operating system a new user interface to do the tricks you see in these videos.

And it all comes back to the philosophical question of what “Windows” really is now.

Microsoft may not think Windows is important anymore, but historically, the company has enjoyed saying it runs on all the things. Back in 2013, it told us that the Xbox One ran Windows. The doomed Surface RT ran Windows in 2012, the original HoloLens ran Windows in 2016, and there were quite a few Windows-based phones stretching back years.

Each time, some Windows users called bullshit because those platforms didn’t run traditional Windows desktop apps — or, in the case of Xbox, any apps at all for years. With the ill-fated Windows RT and Windows 8, they also demanded a Start Menu instead of the touch-centric Start Screen that replaced it.

Each time, the UI or the app compatibility didn’t match up to expectations. In the case of phones, you might have felt betrayed when Microsoft broke promises to upgrade Windows Phone devices to the next version of the OS twice in a row.

Each time, it was true that these devices were running Windows (and not just because Windows is a brand Microsoft owns, and it could technically say a jelly donut contains Windows if it wants). If you asked Microsoft engineers about it at the time — and we did — they would always explain that each device shared more than a little of the same Windows backbone.

But it may soon become even truer that these devices are running the same Windows OS now that Windows is becoming a modular operating system.

We’ll likely learn more about Windows Core in 2020

As Tom and fellow reporters have discovered, Microsoft has been building a new Windows Core OS (WCOS) that will serve as the new modular backbone of Windows. It can be paired with a different user interface for different types of displays by adapting what Microsoft’s calling a Composable Shell, or CShell (say it out loud), to each new interface.

Got a dual-screen device? It might run “Santorini,” the codename for Windows 10X so that it can flip and fold and slide into an array of configurations while intelligently repositioning your apps.

Similarly, the HoloLens 2 augmented reality headset is said to be shipping with “Oasis” to let you pin apps and objects in 3D space on top of Windows Core OS while the gigantic whiteboard-sized Surface Hub 2 may get “Aruba” on top of WCOS in 2020 when its modular “2X” upgrade cartridge ships.

There’s a thought that Windows Core OS could come to regular desktops and laptops with a “Polaris” shell, too, as well as a “GameCore” for Xbox Scarlett, though some believe Microsoft may have abandoned Polaris in favor of sticking with standard Windows 10 for traditional PCs.

Windows 10X is more exciting than any of these, of course, because it’s flashy and new. We already had a HoloLens, an Xbox, a giant Surface Hub, and ways to control each of them. For those, it sounds like Microsoft is largely just porting over the same UI concepts to the new Windows Core OS backbone, whereas Windows 10X gives us neat new tricks like the WonderBar, too.

In 2015, Microsoft called Windows 10 the last version of Windows because Windows is becoming a more nebulous concept than versions like “Windows 8” and “Windows 10” really let on. When the company says something like “The Xbox runs Windows,” it probably wants that to be true in as many ways as possible.

While Microsoft’s already been taking small strides toward making that happen — the current Xbox One actually does run Windows 10 now, and there’s an existing OneCore effort to make Windows more modular — Windows needs to be more flexible and responsive to new device trends than that strategy offered.

Microsoft recently hinted that a new “modern OS” may have one specific benefit for us regular users, too: seamless updates in the background so a Windows Update will hopefully never interrupt your critical work again.

As ever, Microsoft needs the apps

The big challenge may be for Microsoft, which has struggled to get developers to build anything beyond plain, vanilla Windows desktop apps, to convince them to build ones that adapt to all these different screens, forms, and orientations. Surface boss Panos Panay straight-up admitted to us that’s why the Surface Duo will run Android: “It’s pretty simple. Like, literally, you need the apps.”

But that may also be why Microsoft is revealing the Surface Neo and Windows 10X a full year ahead of their planned debut. The company needs to stir up enough interest in the product to prove there’s a market, and Panay tells us it may even put the device in developers’ hands in a few short months. Windows Core OS wasn’t a topic of discussion at the company’s Build 2019 developer conference in May, but the company’s promising more info at Build in 2020.

Getting devs on board may not be as uphill a battle as it would have been a decade ago, back when Microsoft killed off the Courier concept. Then, tablets had barely entered the public consciousness, our modern mobile operating systems were still pretty new, and their chips weren’t anywhere near fast enough to run traditional Windows apps.

But now that the smartphone and tablet have plateaued, new form factors are the talk of tech. Every major company is working on a foldable or dual-screen device or a pair of AR glasses, and that means those new screens are on the tops of many developers’ minds, too.

They’ll just need to decide if Microsoft’s vision for those screens is attractive enough to give Microsoft its due.