CPU (central processing unit)
Beginner
The main chip in a computer or phone that follows a program’s commands one by one, very fast.
Novice
The general-purpose processor that runs the operating system and ordinary programs. It fetches instructions from memory and carries them out; a modern chip holds several CPU cores.
Expert
A general-purpose core optimized for single-thread latency: pipelining, branch prediction, out-of-order execution and deep caches. One die usually carries many cores sharing a last-level cache.
Explained in Instructions and pipelines (Architectures).
See also: Instruction set architecture (ISA), Pipelining.