Is there a document or a website where the Windows registry keys are explained ? Some of them are clear, however when looking for certain features it is difficult to get documentation.
Thanks
It's true that every application vendor has their own settings, but if you look at the registry of a clean Windows operating system, it's all managed by Microsoft.
For the most part, I don't think you'll be able to get the answers as to what a specific setting does. On the other hand, some parameters pertaining to network settings, for example, are quite well documented - take a look at Performance tuning for file servers for example.
In addition, from what I understand, there are also some default values that might not be shown in the registry - and so, if you wish to override those settings, you'll have to create a new key with the appropriate name and assign it a value.
And so, most of the time, searching around the internet for various clues is your best bet. I'd recommend starting with the Microsoft Docs website.
P.S.: Look at this similar question here.