OK, Here is the loaded question........I keep hearing (reading) only to run the processes that need to run to run the system. Is that enough runs in one sentence for you?

I downloaded FSStart and even another program that allowes you to turn off various processes. I am currently running about 40 processes. Other than the rubber bullets, I don't have much of a problem, but before I get off track let me ask the question.
Having limited knowledge about computer systems, how do you know which processes you need to run the system? One of the programs I have defines the processes, but it might as well be written in Greek, and I don't speak Greek.
Is there somewhere I can go to see what processes are required to run the system, like a list or something?
Thanks
Fred