I saw something on TV about this and found it extremely interesting...

Six degrees of separation (also referred to as the "Human Web") refers to the idea that, if a person is one step away from each person they know and two steps away from each person who is known by one of the people they know, then everyone is at most six steps away from any other person on Earth.
http://en.wikipedia.org/wiki/Six_degrees

just thought I'd share