A loan shark is a person who offers loans at extremely high or illegal interest rates, has strict terms of collection, and generally operates outside the law, often using the threat of violence or other illegal, aggressive, and extortionate actions when seeking to enforce the satisfaction of the debt. As a consistent or repeated illegal business operation or "racket", loansharking is generally associated with organized crime and certain criminal organizations.

In finance, a loan is the transfer of money by one party to another with an agreement to pay it back. The recipient, or borrower, incurs a debt and is usually required to pay interest for the use of the money.