295 Exabytes? How much is that and what does that number represent?

Last part first, 295 Exabytes is the amount of data that is stored on this planet as of 2007.  That is counting every country and every form of storage (Hard Drives, Optical Drives, tapes and other various forms of storage).  Simple break down of how big 295 Exabytes are:

Take a 100GB Hard Drive multiply that by 10 MILLION and you get 1 exabyte.  You can imagine the rest of the math to get to 295 exabytes.  For a more graphical breakdown of all this data, check out this page.