Addendum

An addendum is something added to a document to augment or clarify it; it may be a separate section or a separate document linked to the original. The term derives from Latin addendum, meaning "something to be added", from addere, "to add."

In publishing and scholarly work, an addendum is material added after the main text to supply extra information, corrections, or updates. It may be issued as an addendum sheet, a postscript, or appended to the back matter.

In legal and contractual contexts, an addendum is a supplement that modifies or clarifies the terms of an existing agreement without replacing the entire document. It typically requires the signatures of the original parties and becomes part of the contract.

Distinctions: Errata correct errors present in the original text; addenda introduce new information or amendments. In practice, some contracts use "amendment" for substantive changes, with an addendum providing supplementary terms.

Examples include a real estate contract addendum specifying a deadline, a lease addendum adding pet rights, or a book addendum listing changes in a revised edition.