Money-sink (also known as a "gold sink") is a term used to denote a game mechanic that helps to control the inflation rate and in-game economy. Without various money-sinks, the developers would have no viable means of introducing money into, or removing excess coin from, the game's economy. This would eventually lead to a complete breakdown of the economic sub-systems. In a game like World of Warcraft, which is primarily driven by a player-created economy, this could have catastrophic effects. In general terms, think of anything on the luxury side of one's in-game life as a money-sink.