It can be estimated as 10 to the 18th power, or 1,000,000,000,000,000,000 bytes. An exabyte is 1,024 petabytes and precedes the zettabyte unit of measurement. While a 64-bit processor can theoretically use 16 exabytes of address space, exabytes are so large, the units are rarely used in a practical context. For example, it is estimated that all the printed material in the world only takes up about five exabytes.
For a list of all the different units of measurements, view this Help Center article.
Abbreviation: EB