A zebibyte is a unit of data storage that equals 2 to the 70th power, or 1,180,591,620,717,411,303,424 bytes.
While a zettabyte can be estimated as 10^21 or 1,000,000,000,000,000,000,000 bytes, a zebibyte is exactly 1,180,591,620,717,411,303,424 bytes. This is to avoid the ambiguity associated with the size of zettabytes. A zebibyte is 1,024 exbibytes and precedes the yobibyte unit of measurement.
For a list of other units of measurements, view this Help Center article.