A more thorough explanation:

Term: Pars Contractus
Definition: Pars Contractus is a Latin term used in law to refer to a part of a contract. It means that if the parties to a contract agree to reduce their agreement to writing, then the written document becomes a part of the contract. The contract is not considered final or binding until the written document is executed. For example, if two parties agree to sell a car, but they agree to put the terms of the sale in writing, then the written document becomes a part of the contract. The sale is not considered final until both parties sign the written document.