CPU (Central Processing Unit)
If you were to ask people if they had heard of a CPU, about 80% would say yes. But of those people, only about 10% of them would be able to tell you what it is, or what the abbreviation stands for.
The CPU, or Central Processing Unit, is the brain of the computer. As the name suggests, it is responsible for processing all the data from various sources into usable information for other key systems, and also for you, the user.
Considering the job these little guys do, the chips themselves are incredibly small. Squared in shape, a typical CPU will measure about 5cm x 5cm (or 2" x 2") and are usually no more than 1cm thick. But despite their tiny size, they work incredibly hard. In most cases their cooling system is a least 10 times their size.
The modern day CPU has hundreds of little round contacts around the bottom surface, as seen in the top image. These contact with pins on the motherboard, inside a socket specially designed for the CPU. Each motherboard has a specific socket type, and only CPU's of that socket type are compatible with that board.
In the older CPU's, the contacts used to be on the motherboard and the pins were on the CPU. Fortunately this has now changed, as many people discovered the hard way that putting your CPU in the wrong way and bending the pins was a good way to throw away a couple of hundred dollars.
In a fully assembled system, you wont be able to see the CPU when you open the case. It will be covered up by the heatsink and fan cooling system on top of it. Without this cooling system, a CPU can heat up to many hundred degrees in a matter of seconds. These sort of temperatures can easily destroy a processor chip, and in some cases, even cause them to explode.
In this internal image of a computer system, you can see in the upper right region of the motherboard, just below the four RAM rails, there is a large, black, square-shaped object with a fan inside. This is part of the cooling system for the CPU. At the top is the fan and beneath that there is a heatsink. This is a light metallic structure with several thin fins that absorbs heat from the CPU beneath it and allows it to be dispersed by the air blown down through them by the fan on top. The CPU itself is fastened into the motherboard beneath this cooling system.
CPUs come in various different designs, though from the outside, most appear very much the same. As mentioned before, each CPU is designed to fit into a specific type of motherboard socket, and so they are incompatible with any other socket-type board. CPUs also have various different operating designs, some with single cores and others with multiple cores. CPU's with more than one core are capable of carrying out more than one process at a time. In short, they can multitask.
CPU's are also rated with various different speeds, which are measured in Gigahertz (Ghz). Basically the higher the Ghz rating on a processor, the faster it can put through data and information. However processors with multiple cores may have a slower Ghz rating than a single core processor and still be a faster chip, since they can put through more data at a time.