Trivia : Six Degrees of Separation

Last year I started reading a book (haven't finished reading it yet) entitled : six pixels of separation, it's about the internet and the online social network, its importance and uses. I think the title was taken originally from " six degrees of separation". 


What is "six degees of separation"?


Six degrees of separation refers to the idea that everyone is on average approximately six steps away, by way of introduction, from any other person on Earth, so that a chain of, "a friend of a friend" statements can be made, on average, to connect any two people in six steps or fewer. 

Update on "six degrees of separation" :

Adding a new chapter to the research that cemented the phrase “six degrees of separation” into the language, researchers at Facebook and the University of Milan reported in November 2011 that the average number of acquaintances separating any two people in the world was not six but 4.74.

The research was based on a cohort of 721 million Facebook users. The researchers used a set of algorithms developed at the University of Milan to calculate the average distance between any two people by computing a vast number of sample paths among Facebook users. They found that the average number of links from one arbitrarily selected person to another was 4.74. In the United States, it was just 4.37.

Six degrees of separation

Source : Wikipedia and The New York Times