Microsoft is taking the next steps in its "One Windows" vision with an internal project called "Windows Core OS" that turns Windows 10 into a fully modular platform and lays foundations for the future of Windows.

Updated September 29 2017: Several sources have come forward and told us the "Andromeda OS" effort is now internally referred to as "Windows Core OS." We've updated this article to reflect this.

Windows is now over 30 years old, which is beyond ancient in technology years. As a result of this, Windows itself is encumbered by features, functions, and components that some devices today may no longer need. In an industry where new device types are being introduced all the time, Windows itself is too old and heavy to be able to adapt to those new devices (an example of which are smartwatches) quickly enough. As it turns out, Microsoft is aware of this and is working on something internally that looks to solve this problem.

Over the last several months, I've been talking to multiple sources about something internally referred to as "Windows Core OS." According to these sources, Windows Core OS (WCOS for short) is the future backbone of Windows and is a monumental step forward in making Windows 10 a truly universal OS. In short, WCOS is a common denominator for Windows that works cross-platform, on any device type or architecture, that can be enhanced with modular extensions that gives devices features and experiences where necessary.

In layman's terms, its ultimate goal is to make Windows 10 much more flexible, allowing it to be installed on a wider variety of devices without being based on specific, pre-existing product variants. As a result of this, Windows itself can become smaller depending on the device, the OS itself can be built faster, and devices won't be encumbered by components and features they don't actually need; speeding up overall performance in the process on smaller or less capable devices.

As it currently stands, OneCore and the Universal Windows Platform are the only true universal elements of Windows 10. Everything else is specific to the many variants of Windows. For example, Win32 programs are specific to Windows on the desktop and aren't found on Windows Mobile. With WCOS, Microsoft wants to remove these specific product variants, and turn Windows 10 into a fully modular platform by componentizing the OS.

As a result of this full modularity, individual Windows 10 product variants such as Windows 10 Mobile or Windows 10 on Xbox become redundant. WCOS allows Windows 10 to be configured and built for a specific device without it having to be its own variant. It gives Microsoft and hardware makers the flexibility of building versions of Windows 10 with different features and functions, quickly and efficiently.

What does this mean for me?

Windows 10 as it is today has a few different variants of itself. It's not one OS that's shared across devices. Windows 10 Mobile and Windows 10 desktop are two different variants of Windows 10, for example. Now, these different variants do share universal elements, such as OneCore and the Universal Windows Platform, but the OSs themselves aren't the same. WCOS removes these different variants and gives us a universal base that can be built upon. If you want Windows on a phone, instead of using Windows 10 Mobile, you would simply use "Windows 10" with components that make sense for a phone device. It's the next steps in Microsoft's modularity of Windows, which has been ongoing for years at this point.

In fact, it's very similar to how Windows 10 Mobile itself is handled today. Windows 10 Mobile is provided in separate packages to OEM's, which gives said hardware makers the flexibility to pick and choose which OS features and functions (such as Continuum) are bundled onto a device. It's the same idea here with WCOS, except it's applied to all of Windows 10 instead.

Right now, if an OEM wants to make a device running Windows, it has to choose from a number of pre-defined variants of Windows 10 that Microsoft has already built. That includes things like Windows 10 Home, Windows 10 Pro, Windows 10 S, Windows 10 Mobile, Windows Server, Windows 10 IoT, and many more. This can sometimes be a very limiting factor for OEMs. WCOS makes it so hardware makers aren't limited to pre-defined variants, and can pick and choose features and functions from each for their devices instead.

WCOS opens the door to many new configurations of Windows that previously weren't possible. Of course, Windows 10 desktop SKUs such as Pro and Enterprise will continue to exist, with all the same functionality and features you'd expect from a desktop OS. Microsoft won't be taking functionality away, and it won't be de-emphasizing desktop with WCOS.

Windows Central understands that the initial introduction of WCOS will be mobile-focused, and is internally pegged to be ready sometime in 2018. A theoretical Surface phone running Windows 10 built with WCOS wouldn't be running Windows 10 Mobile or Windows 10 desktop, it would be running "Windows 10" with whatever components Microsoft deems fit. That may include Win32 components, or it may not. It will depend on the kind of device Microsoft, or hardware makers, are planning to build.

The work Microsoft is doing to Windows 10 with WCOS will help move Windows into the twenty-first century, where devices of all shapes, sizes and power capabilities are being introduced all the time. Windows today can't run on everything because it's just too big and heavy. Even the smallest variants of Windows 10 today can be too much for some device types, such as smartwatches. WCOS will change this.

As mentioned above, we're hearing the first iteration of WCOS will be for mobile-type devices such as phones, tablets, and wearables, with WCOS for desktop and Xbox devices coming later. WCOS, along with work Microsoft is doing with CShell, is a huge leap forward for Microsoft's "One Windows" vision. OneCore and the Universal Windows Platform were the first Windows 10 elements to be universal, and now Microsoft is taking the next steps in that vision with WCOS and CShell.

The future of Windows

WCOS and CShell are laying the foundation for Windows into the next decade and beyond. WCOS will help kick-start Windows on modern, mobile devices, along with modernizing Windows itself for new device types that may show up over the next several years. Microsoft needs a flexible, configurable and nimble OS and Windows today isn't that. WCOS will make it that, and that's incredibly exciting.

We already know Microsoft is prototyping new mobile hardware internally, which is often referred to as simply "Andromeda" on the web. Could Microsoft be planning to release a mobile device next year, powered by Windows 10 with WCOS that showcases to hardware makers and the rest of the world what can be done? We're yet to find out. Regardless of who makes new mobile devices running Windows, whether they be phones, tablets, wearables or something else entirely, WCOS will give them a stage to do it.

It is important to stress that WCOS isn't a consumer-facing feature, and won't be something Microsoft is planning to market openly. It's an internal platform that makes Windows far more flexible, allowing Microsoft and hardware makers to build versions of Windows 10 that previously weren't viable. As always, Microsoft may decide to pull the plug or delay its WCOS efforts at any time, too, so keep that in mind.

What are your thoughts on Windows Core OS? Let us know in the comments.