Something I have been puzzled about is this: how exactly does a computer regulate and tell time? For example: if I were to write a program that did this: Do 2+2 then wait 5 seconds How does the processor know what "5 seconds" is? How is time measured in computer systems? Is there a specific chip for that sole purpose? How does it work? Thanks for any replies; I'm really interested in computer science, and would love any help you could give me =D.