What does "6-Degrees" mean?

The term "six degrees of separation" refers to the idea that everyone on Earth can "reach" any other person through a chain of connections, that on average is approximately 6 people long.

Your friend is a 1-degree connection to you; your friend's friend is a 2-degree connection to you; your friend's friend's friend is a 3-degree connection to you, and so on. A good number of research studies show that a chain of "a friend of a friend" connections can connect, on average, any two people in six steps or fewer.

The trivia game Six Degrees of Kevin Bacon and the DropaBalm '6-Degrees of you' StoryNet Kit are based on this idea.