This document discusses different types of contracts, including social contracts, private contracts, international contracts, and municipal contracts. A social contract refers to an agreement among members of a society, such as a country's constitution or laws. A private contract is an agreement between two or more individuals for private purposes, governed by contract law. An international contract involves two international actors and international importance. Municipal contracts are agreements between citizens of a state, governed by that state's laws. The document also notes that all agreements must be kept according to the Latin principle of pacta sunt servanda.