"Ponzi schemes" or "pyramid schemes" are illegal fraudulent schemes in which people are recruited to make payments to the person who recruited them while expecting to receive payments from the persons they recruit, usually without any product or service delivered. The scheme ultimately collapses due to the inability to recruit any more participants to the schemes. The term "Ponzi" refers to Charles Ponzi, a criminal in the early 20^th century that used such a scheme to defraud innocent investors.