2.1. The Processor or CPU

The processor is the component that performs virtually all of the computation and controls the behaviour of most of the other devices. The most common processors are Intel's Pentium and Celeron family and AMD's Athlon and Duron. The crudest measure of a processor's power is its "clock speed", given in Megahertz (MHz) or Gigahertz (GHz, 1GHz = 1000MHz). These are the figures that will appear in advertisements. Generally speaking, the faster the clock speed, the faster the computer will be.

The highest speed processors available at any time tend to be disproportionately expensive, so most people tend to buy a slightly slower system.

2.2. Memory or RAM

RAM is the fast memory that the computer uses to temporarily store information for the tasks it is performing. Unlike the hard drive, RAM relies on power being supplied to retain information. When you switch the computer off the information is lost (but don't panic, it can be kept on the hard drive). The size of RAM is measured in Megabytes (Mb) and, as with processor clock speed, more is usually better.

2.3. Hard Drive

The hard drive is a magnetic storage device that can hold programs and information when the computer is turned off. Information is exchanged between the memory and hard drive according to the needs of the tasks being performed (remember RAM is fast so the processor can find information quickly there). The size of a hard drive is measured in Gigabytes (Gb) and, again, more is better.

2.4. Monitor

The monitor is the device that displays information from the computer in the form of windows, icons, images and text. There are two principal types of monitor at present: CRT monitors (the ones that look like televisions) and LCD monitors. Advertisements will quote monitor sizes which is the distance measured across the diagonal of the screen in inches and the resolution in dots per inch. Larger screens can be useful for working with graphics or for desktop publishing.

2.5. Graphics Card

The purpose of a graphics card is to present information in a visual form on the monitor of the computer. The specification of the graphics card will affect the resolution that can be displayed on the monitor and the "refresh rate" of the display. The refresh rate is the number of times per-second that the screen is re-drawn - a high refresh rate produces a flicker free display.