Non-nerd's Guide to Computers/processor
The CPU (At the Heart of the Process)
As far as computing power goes, the Central Processing Unit (CPU) is the most important component of a computer system, while your computer can fail if any other component breaks. When you run your web browser, write your poems, doodle on graphics program such as Paint, etc. you're using a CPU (for graphics you're also likely to use a GPU, that supplements the CPU). The CPU carries out each instruction of the computer's program in sequence, performs the required arithmetic and logical operations, and directs the Input/Output (I/O) operations of the system. In short, the CPU has been compared to the brain in people, while there are also fundamental differences. The CPU doesn't "think", it only follows strict orders from the so-called program it "runs".
Two typical components of a CPU are: the (ALU) Arithmetic Logic Unit, which performs arithmetic and logical operations, and the (CU) Control Unit, which fetches instructions in sequence from memory, then decodes and executes them, using the ALU if necessary.
Personal computers have a CPU contained in a single microprocessor chip socketed on the motherboard, bearing a heat-sink with its own fan (a fan wasn't necessary historically and neither used in some recent computers) to dissipate the considerable heat generated by modern high speed CPUs.