Windows license?

Question

Microsoft

Questions of this kind. How do computer hardware manufacturers buy Windows OS from Microsoft?
For example, HP sells a PC already preinstalled with OS Windows 7, it has been slightly modified. For example, when you start the welcome screen, the image is HP and there is already HP software.
HP specifically make a request to Microsoft to make them such an OC?
And what kind of license is usually purchased by manufacturers?

Answer 1

vendors buy oem and edit them Windows AIK or WAIK

Answer 2

There are OS versions for distributors. As for the rest of the points, I'm not sure. Most likely, hardware manufacturers ask MS to make an assembly for them, which they will install on their computers, most likely, even the drivers are preinstalled there. This is beneficial to MS, so there is nothing surprising in doing this.