What do you want to know about the Windows kernel?

I am by no means a kernel expert, but I do have a couple years of experience working with the Windows kernel and I have done a fair amount of reading about the internals of Windows and operating system development in general.  And of course I have looked over a large amount of the Windows code.

While I've spent the last four months or so getting dug into my position, I need to expand my horizons and choose some areas of the Windows kernel to learn about.  I was hoping all of you could help me out by leaving comments with your questions about the Windows kernel.  Now, if you are driver developer with over five years of experience there is probably no way I can tell you something you don't know.  But, if you are an application developer wanting to know more about the internals of Windows or someone that knows a lot about operating systems theory who is wondering how Windows does something I may be able to help out.

I'll try to answer as many questions immediately as I can myself; then I will pick from the remaining questions to research (by talking to the person who wrote the Windows component) and get back to you with an answer.  I would prefer to stick to general questions about Windows components, no function or parameter specific questions or anything of that sort please.

Of course I won't release any information that isn't public knowledge.  And, as always, please be respectful when asking your questions.