An addendum is an addition to an existing document that provides additional information or corrections. It may be used to modify or update a contract, policy, or other document. It is typically added as a supplement to the main document to clarify details, make changes, or add new information. There are several types of addendum, including purchase addendum, loan addendum, lease addendum, and amendment addendum. A purchase addendum is used to provide additional information or terms to an existing purchase agreement. A loan addendum is used to provide additional information or terms to an existing loan agreement. A lease addendum is used to provide additional information or terms to an existing lease agreement. An amendment addendum is used to make changes to an existing contract or other document.