The biggest takeaway Microsoft is hoping to deliver this week, sources say, is that Windows 10 is built on a single, common "core" (known internally as "OneCore") that will work across a variety of devices, from phones, tablets, PCs, large-screen displays like the company's Perceptive Pixel multitouch-screen devices, and ultimately, Xbox.
OneCore implies more than just the common kernel that Microsoft touted as part of its Windows 8/Windows Phone 8 stories. In addition to the OS kernel, OneCore also includes the dynamic link libraries (DLLs), application platform layer and other pieces of the operating system. Microsoft's pitch to developers with Windows 10 will be they can target the same core environment with their apps, and those "Universal" apps will work across a range of screen sizes. These apps will be available in a single store, rather than separate Windows, Windows Phone and Xbox stores.