CPU & Power Supply (internal)

The CPU (processor) is the brains of the whole computer. It is the thing that processes all the information you throw its way. The CPU will generate lots of heat from doing all the work so all processors are equiped with a heatsinc, and typically a fan, to cool it down to a safe temperature. The speed that a CPU processes data is measured in Mhz (mega-hertz) and Ghz (giga-hertz). Today GHz is the measure you most often see. However, there is a second main factor in how fast your computer will process information. All CPU's have a second chip very close by called a system bus (or front side bus). The role of the bus is to filter and send the processor information from other components of the computer. The bus is also measured in Mhz (and Ghz when it gets that fast). Nearly everything the computer does goes through the CPU, but some things like graphics are starting to be completely processed by the graphics card.

The power supply is of course an essential part of every computer for obvious reasons. It is what supplies the computer with power. Really self explainitory. It has several plugs coming out of it to give power to the drives, and mother board.