What is the basis of the Chess.com database?

I've encountered numerous messages like this when using the Analysis function: "Postition not found in the database." Of what does the database consist? Chess.com games? What are considered to be "master games"? I'm a relatively neophite player, yet most of my "positions" aren't found in the database. What gives?

The Chess.com game database (Games/Openings Explorer) consists of Master games which in general are games involving 2200+ rating players. When you go to http://www.chess.com/explorer/index.html you have three different sort choices from Master games, to other Chess.com games, to your own Chess.com games.

Thanks! I guess that explains why my weird positions aren't in the database. No 2200+ player would get herself in such positions.