A kilobyte is a unit for measuring computer information — how much text, sound, or picture a machine is holding or sending. The short form is KB. In a lot of computer talk, one kilobyte means 1,024 bytes, not 1,000, because machines like powers of two, and 1,024 is two multiplied by itself ten times. That is the sense here. Though actually, in ordinary science kilo- means exactly 1,000, and some people — especially when they talk about disks, plans, or download sizes — treat a kilobyte as 1,000 bytes. That mix has caused years of quiet argument. A newer word, kibibyte, was made for the 1,024 meaning, but most everyday English still says kilobyte and lets the number be a little messy. By today’s standards one kilobyte is small: a short email with no pictures might be only a few kilobytes.

千位元組（KB）。台灣說「位元組」，中國大陸較常說「字节」。