Computer memory, whether it consists of RAM chips, magnetic "hard" and "floppy" disks, or optical disks like CD-ROMs or DVDs, is really just a huge collection of ones and zeros. Read and write heads, miniature versions of the heads on your cassette tape recorder or VCR, are used to flip the magnetic polarities of tiny specks of metal on the disk's surface, or to dig tiny "pits" in the surface of a plastic CD. Specks which are polarized one way are used to represent zeros, and those polarized the other way to represent ones. The same goes for the pits and the surfaces of the CDs. By combining groups of ones and zeros, you can represent just about any sort of data you wish.

Computers use the Binary (base two) number system to represent everything from the keys on your keyboard to the picture elements (pixels) of a photograph or drawing. The binary system corresponds more easily with the Hexadecimal (base 16) system than with the Decimal system we use every day. Perhaps we think in tens because we have ten fingers. Some of the ancient Greek philosophers thought ten was the "perfect number", but as you can see, you can represent up to sixteen possibilities using four columns in Binary numbers, so Hexadecimal is more a more perfect match when it comes to computing.

You will need to be able to recognize Hex numbers if you intend to do any serious Web page design, or if you will be responsible for a network server.

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