My sources

How many people use Facebook - http://www.digitalbuzzblog.com/facebook-statistics-stats-facts-2011/

History of Facebook - http://www.businessinsider.com/how-facebook-was-founded-2010-3?op=1

Why we use Facebook - http://www.readwriteweb.com/archives/study_why_do_people_use_facebook.php

Benefits of having "Friends" - http://jcmc.indiana.edu/vol12/issue4/ellison.html

Facebook and Society - http://www.nczonline.net/blog/2008/10/27/facebook-the-transparent-society/