Computer Memory Definitions What is a Kilobyte? Megabyte? Gigabyte? Terabyte? SUMMARY: This tip defines the computer memory terms 'kilobyte', 'megabyte', 'gigabyte', and 'terabyte'.   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, and terabyte 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. 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, and terabytes, and that is why when you buy a hard drive with, for example, 400 gigabytes, you may not be getting exactly the amount of room that you think!   Add: Del.icio.us | Digg | Furl | My Yahoo!   Discuss This Tip Print This Tip Get E-Mail When New Tips are Online Return to the Computer Memory Definitions page.