ISO 22000 is the international standard that lays out requirements for a Food Safety Management System. It brings together the principles of Hazard Analysis and Critical Control Points (HACCP) with the general structure used in management-system standards like ISO 9001.
It applies to any organisation across the food supply chain, from farm to fork, that wants to demonstrate it can control food safety hazards.
It shouldn't be confused with a generic Quality Management System, which is ISO 9001, or with HACCP certification on its own, since ISO 22000 actually incorporates HACCP as one of its core building blocks rather than being identical to it.