The document discusses the legal framework around copyright and open licensing that powers Wikipedia, explaining that Wikipedia uses exclusively open content that is either in the public domain, licensed under open licenses like CC BY-SA, or falls under the fair use exception. It provides an overview of copyright, the public domain, open licensing terms like CC0 and CC BY, and best practices for contributing content to Wikipedia to ensure it follows these open rules. The goal is to help people feel more confident about editing and contributing text and media to Wikipedia and its sister projects.