Computers and storage mechanisms (CD-ROMs, hard drives, USB flash drives, DVD-ROMs, etc.) need to hold much larger values than what a byte can hold (0-255). Thus, the terms kilobyte, megabyte, gigabyte, terabyte, petabyte, and exabyte were created to represent such large amounts of information.

The definition of a kilobyte is 1,024 bytes; however many people think of it as 1,000 bytes.

The definition of a megabyte is 1,024 kilobytes; however many people think of it as 1,000 kilobytes.

The definition of a gigabyte is 1,024 megabytes; however many people think of it as 1,000 megabytes.

The definition of a terabyte is 1,024 gigabytes; however many people think of it as 1,000 gigabytes.

The definition of a petabyte is 1,024 terabyte; however many people think of it as 1,000 terabytes.

The definition of a exabyte is 1,024 petabyte; however many people think of it as 1,000 exabytes.

Why the confusion? There are two numbering systems in play. Strictly in "computerese", a base 2 system is in play, so that one kilobyte is 2 to the power of 10 bytes, or 1024 kilobytes. However, many hardware manufacturers, including hard drive manufacturers think of a kilobyte as only 1,000 bytes, or 10 to the power of 3 bytes.

This is the same with megabytes, gigabytes, terabytes, petabytes, and exabytes, and that is one reason why when you buy a hard drive with, for example, one terabyte, you may not be getting exactly the amount of storage room that you think!

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