A document that makes additions or amendments to an existing contract. It is used to introduce changes, clarify terms, or modify provisions without negating the original contract. An addendum becomes a legally binding part of the contract once all parties sign it. This document is particularly useful when parties want to update or change the terms of a contract without having to rewrite and sign a new one entirely. It ensures that specific terms are tailored to the evolving needs or circumstances of the contracting parties, while the main structure and spirit of the original agreement remain intact.