text: It means through a chain of no more than 6 people you can connect yourself to any person in the world.  It may not be universally true, and it requires certain channels of communications (eg. a famous person you know is a better link than Joe Blow).\n\nFor example, I met my member of parliament in Canada.  He works with the Canadian Prime minister.  The PM knows the US president.  Shrub has (probably) met your senator.  And you could meet your senator.  That's a separation of only four people to get from me to you.