when you negotiate services with a client or supplier, the process can take time and culminate in a contract that spells out the obligations and requirements of all signatories. a master service agreement (msa) is a contract that spells out most but not all of the terms between the signing parties. its purpose is to speed up and simplify future contracts. future agreements need spell out the differences from the contract and might require only a purchase order. they can affect a wide area such the country or a state, with subset terms negotiated at the local level.