Since the release of Windows 10 in 2015, Microsoft declared it would not 'follow the same path' and aimed for a fresher approach by amalgamating Windows 10 for PCs with Windows 10 Mobile and Xbox Live infrastructure. Polaris could very well be the next step in this new trend.
So, to understand what Windows Polaris is, readers can refer to the article below by Mytour.
Windows Core OS
The idea behind Windows Core OS is to transform Microsoft's old Windows platform into a more cohesive one, suitable for all types of devices. When OEMs want to develop new devices, they have to use pre-packaged versions of Windows, which may contain features they don't need. Windows Core OS is more consistent, efficient, and notably, lighter.
According to Mary Jo Foley of ZDNet, Windows Core OS doesn't support running Win32 applications (more commonly known as traditional applications) but only runs Universal Windows Platform (UWP) apps. However, because Windows Core OS is designed as a modular system, adding support for traditional applications as modules is possible.
According to Mary Jo Foley, Windows Core OS was previously known as AndromedaOS, an operating system rumored to run on Microsoft's rumored mobile device 'Andromeda'.
C-Shell: Modular Interface
Composable Shell, also known as CShell or C-Shell, is another project related to Windows Core OS.
Currently, devices running 'variants' of Windows all have separate interfaces integrated into the operating system. Specifically, PCs have their own interface, Xbox One has the Xbox dashboard, and Windows mobile devices have interfaces tailored for the mobile platform.
C-Shell is a shared interface running on the Windows Core OS. It is compatible with all types of devices in real-time. In other words, Microsoft is developing a smart interface that can automatically adjust across all devices used by users.
Polaris: Desktop Interface for PC
In simple terms, C-Shell consists of multiple 'interface layers' for different devices. Polaris is considered the interface layer for PC. In other words, Polaris is the Windows PC experience built on top of C-Shell and Windows Core OS.
Rumors suggest there will be 3 versions of Core OS, including Andromeda for mobile device interfaces, Aruba for Surface Hub interfaces, and Oasis for Windows Mixed Reality devices like HoloLens.
Windows Core OS exclusively runs on new devices
Previously, specifically with Windows 10, Microsoft compelled users to upgrade to new versions. According to a post on LinkedIn, the software giant stated that Core OS will run on new devices, meaning users won't have to upgrade to a new version of Windows.
Sources from Windows Central suggest that the initial release of Windows Core OS will primarily focus on mobile devices. In the long run, all new Windows devices, including PCs and laptops, will run this new operating system.
So, this article by Mytour has just answered your question about what Windows Polaris is. Additionally, if you have any inquiries or questions like What is Windows 10X, readers can leave their comments below the article.