Andrew Weinreich launched “Six Degrees” in 1997. Based on the theory that every person in the world could be connected to each other by just six degrees of separation, the new web service encouraged members to share personal profiles and contacts. Now regarded as the first recognizable social networking service, Six Degrees grew to over one million members but closed in four years. MySpace and LinkedIn gained prominence in the early 2000s. By 2006, Facebook and Twitter first became available worldwide.