When you have a business where customers contract you to perform a service, you need a legally binding agreement to spell out of the terms and conditions of the business relationship. According to "All Business," a business agreement serves as a guide that all parties to the agreement must follow. Generally, one party draws up the agreement and both parties sign the it as an acknowledgment of the terms and conditions it contains.
Conventions and Treaties signed by signatories of states bind private actors to the terms of that agreement through the domestic application of the treaty provisions. These agreements may be bilateral (between two countries/states) or multilateral (between three or more countries/states).