I'll start by talking about computers in general. The innards of today's desktop computers include, among other things, the central processing unit (CPU), random-access memory (RAM), read-only memory (ROM), and the hard drive. Here's what they do.
The CPU is the computer's brain—the big computer chip that makes most of the calculations that allow the computer to perform so many wondrous tricks. Unlike the human brain (or a carp's brain, for that matter), the CPU isn't capable of making decisions or being proactive; it simply does what it's told to do. Although this quality is an admirable one in football players and toddlers, it's not the kind of thing to gloss up an otherwise dull résumé. No, what makes the CPU so spectacular is that it does what it's supposed to do at incredible speed. Any CPU worth its salt carries on with nary a flinch when asked to execute thousands of instructions in the blink of an eye.