A small-world network is a type of graph in which most nodes are not neighbors of one another, but most nodes can be reached from any other by a small number of connections. This small world phenomenon was first discovered by Watts and Strogatz who measured that in fact, many networks have a small average shortest path length, but also a clustering coefficient significantly higher than expected by random chance. The small-world phenomenon is behind the famous six degrees of separation hypothesis and many real-world networks are well-modeled by small-world networks including, social networks, website links on the Internet, wikis such as Wikipedia, and gene networks in the human body.