A money services business (MSB) is a legal term used by financial regulators to describe businesses that transmit or convert money. The definition was created to encompass more than just banks which normally provide these services to include non-bank financial institutions.
An MSB has specific meanings in different jurisdictions, but generally includes any business that transmits money or representatives of money, provides foreign currency exchange such as Bureau de changes, or cashes cheques or other money related instruments. It is often used in the context of Anti Money Laundering (AML) legislation and rules.
References
Money services business Wikipedia(Text) CC BY-SA