Ponzi Scheme: Named after Charles Ponzi, who ran such a scheme in 1919-1920. A Ponzi scheme is an investment scheme in which returns are paid to earlier investors, entirely out of money paid into the scheme by newer investors. Ponzi schemes are similar to pyramid schemes, but differ in that Ponzi schemes are operated by a central company or person, who may or may not be making other false claims about how the money is being invested, and where the returns are coming from. Ponzi schemes don't necessarily involve a hierarchal structure, as in a pyramid scheme; there is merely one person or company that is collecting money from new participants and using this money to pay off promised returns to earlier participants.