Central Processing Unit. The part of an electronic circuit analogous to the brain. It controls the functions of an entire computer structure. Like all ICs (Integrated Circuits), a CPU is made up of thousands of microscopic transistors housed inside a resin or plastic shell. Because of the high amounts of heat that modern CPUs radiate, they are usually equipped with heat-dissipation systems. These consist of either aluminum heat sinks, small fans, or liquid cooling systems.
The processing power of modern CPUs nearly doubles about every two years. As of 1981, the most common intel CPU ran at a "whopping" 4.77 MHz (4.77 million cycles per second). Modern CPUs run at several GHz. Most modern CPUs, including those produced by AMD and Intel, contain several processing cores hooked together in parallel (within a single chip).
In the episode "Strange Things Happen at the One Two Point" of Terminator: The Sarah Connor Chronicles, an older CPU, disguised to look more advanced, was used to swindle Sarah Connor out of $500K. A man named Alex Akagi, owner of Dakara Systems, hired an actor to "sell" him the chip in order to get the money from Sarah, who was posing as an investor.