A unit of measurement equivalent to one thousand bytes of computer memory or disk capacity. For example, a device that has 256K of memory can store approximately 256,000 bytes (or characters) at one time. In decimal systems, kilo stands for 1,000, but the computer world is based on a binary system of twos instead of tens.
So, a kilobyte is actually 1,024 (210) bytes. To distinguish between a decimal K (1,000) and a binary K (1,024), the IEEE has suggested using a small k for a decimal kilo and a capital K for a binary kilo. In international English, outside the U.S.A., the equivalent unit is sometimes seen as "KB" or "kbyte." Note: Kb is kilobit, KB is kilobyte.