I refer you to the Oracle of Bacon for understanding. The default will tell you how many actors separate Kevin Bacon from any given actor. For example, if you put in "Elvis Presley" you will find that they both worked with John Wheeler of different movies (a Bocon Number of 2). If you want to know, click the "How It Works" tab on the left. Mark Ruffalo worked with him on the same movie, for a Bacon number of 1.