Perhaps and overview of the Austrian Business Cycle Theory is in order to explain one of the most prominent causes of the cycle itself. Short version: Credit expansion in the form of artificially-low interest rates sends a market signal that there is an abundance of stored wealth, resulting in business expansion and investment, especially in infrastructure projects like housing. people borrow in anticipation of epople spending this stored wealth, but eventually the reality sets in when no one turns up to buy what has been produced. This results in a crunch as malinvestments resulting from the distorted information must be liquidated. This crash is a correction, but government policies seek to put off this necessary rebalancing. The boom is never seen as the problem, and the bust is the proof that more government management is needed, somehow.