Kibibyte (KiB)

Exactly 1,024 bytes, being two to the power of ten, and the binary counterpart to the decimal kilobyte.

For decades the kilobyte meant 1,024 bytes to a programmer and 1,000 bytes to everyone else, because computers count in powers of two while the metric prefixes count in powers of ten. The discrepancy is small at the kilobyte and grows steadily upward: a terabyte and a tebibyte differ by about ten per cent. Storage manufacturers quote the decimal figure and operating systems have often reported the binary one, which is why a new drive always appears smaller than the box claimed. The International Electrotechnical Commission introduced the kibibyte and its siblings in 1998 to end the ambiguity, and their adoption has been patchy at best.