Try:
http://www.wikipedia.org/wiki/Unix_epoch (and then
http://www.wikipedia.org/wiki/UTC,
http://www.wikipedia.org/wiki/Epoch)And
http://www.google.co.nz/search?hl=en&...y&meta=Note that the UNIX epoch is based on 00:00:00 UTC on January 1 1970, itself a datetime that doesn't occur at the same instance everywhere in the world.
