According to the definition by the U.S. Treasury Department, money laundering crime refers to a complex sequence of banking transfers or commercial transactions to make illegally obtained money (i.e. "dirty money") into legal money ("clean money").
The process of laundering money typically involves three stages: placement, layering, and integration. First, the illegal funds are put into the legitimate financial system. Then, layering conceals the source of the money through a series of banking transfers or commercial transactions; last, the now laundered money is used from the legitimate account to be put in for whatever purposes.