A yottabyte (derived from the SI prefix yotta-) is a unit of information or computer storage equal to one septillion (one long scale quadrillion or 1024) bytes. It is commonly abbreviated YB. At this time, no computer has achieved one yottabyte of storage. In fact, the combined space of all the computers in the world does not amount to one yottabyte. According to one study, the world stores 161 exabytes as of 2006, with 988 exabytes projected by 2010.[1] When used with byte multiples, the SI prefix may indicate a power of either 1000 or 1024, so the exact number may be either:
1 septillion, or 1,000,000,000,000,000,000,000,000 bytes — 10008, or 1024, or
1,208,925,819,614,629,174,706,176 bytes — 10248, or 280.
The term "yobibyte", using a binary prefix, has been proposed as an unambiguous reference to the latter value.