(PB) A unit of data equal to one quadrillion bytes
but see binary prefix for other definitions. A petabyte is
10^15 bytes or 1000^5 bytes or 1000 terabytes.
As of 2013-11-05, the Internet ArchiveWayback Machine
contains almost two petabytes of data.
A petabyte is the amount of data that would be required to store a
2000 by 1600 pixel image of every one of the 314 million people
living in the USA in 2012.
1000 petabytes are one exabyte.