|Unit of Digital Information Storage|
|Zettabyte|| 1021 Bytes|
|(larger units were proposed but have not yet formally been adopted by the BIPM)|
A zettabyte (ZB), derived from zetta- prefix, is an International System of Units (SI) unit of digital information storage equal to 1000 exabyte. This unit is part of IEC 80000-13 (International System of Quantities) which requires this unit to always equal 1000 exabyte. A closely related unit, zebibyte, is used to represent 1024 exbibytes.