Exabytes

The exabyte is a multiple of the unit byte for digital information. In the International System of Units (SI), the prefix exa indicates multiplication by the sixth power of 1000 (10¹⁸). Therefore, one exabyte is one quintillion bytes (short scale). The symbol for the exabyte is EB.

A related unit, the exbibyte, using a binary prefix, is equal to 1024⁶ (=2⁶⁰)bytes, about 15% larger.

Allegedly, "all words ever spoken by human beings" could be stored in approximately 5 exabytes of data. This claim often cites a project at the UC Berkeley School of Information in support (although this project is now outdated and therefore not entirely accurate). The 2003 University of California Berkeley report credits the estimate to the website of Caltech researcher Roy Williams, where the statement can be found as early as May 1999. This statement has been criticized.Mark Liberman calculated the storage requirements for all human speech at 42 zettabytes (42,000 exabytes, and 8,400 times the original estimate), if digitized as 16 kHz 16-bit audio, although he did freely confess that "maybe the authors [of the exabyte estimate] were thinking about text".

Earlier studies from the University of California, Berkeley, estimated that by the end of 1999, the sum of human-produced information (including all audio, video recordings, and text/books) was about 12 exabytes of data. The 2003 Berkeley report stated that in 2002 alone, "telephone calls worldwide on both landlines and mobile phones contained 17.3 exabytes of new information if stored in digital form" and that "it would take 9.25 exabytes of storage to hold all U.S. [telephone] calls each year".International Data Corporation estimates that approximately 160 exabytes of digital information were created, captured, and replicated worldwide in 2006. Research from University of Southern California estimates that the amount of data stored in the world by 2007 was 295 exabytes and the amount of information shared on two-way communications technology, such as cell phones in 2007 as 65 exabytes.

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