Milgram’s idea was to test this question with a chain letter. For one experiment, he got the names of a hundred and sixty people, at random, who lived in Omaha, Nebraska, and he mailed each of them a packet. In the packet was the name and address of a stockbroker who worked in Boston and lived in Sharon, Massachusetts. Each person was instructed to write his name on a roster in the packet and send it on to a friend or acquaintance who he thought would get it closer to the stockbroker. The idea was that when the letters finally arrived at the stockbroker’s house Milgram could look at the roster of names and establish how closely connected someone chosen at random from one part of the country was to another person chosen at random in another part. Milgram found that most of the letters reached the stockbroker in five or six steps. It is from this experiment that we got the concept of six degrees of separation.
Malcolm Gladwell —Six Degrees Olof Lois Weinberg (The New Kings Of Nonfiction, edited by Ira Glass)