Founded in 1986, PD Info (taken over in early 1999 by Haven Sound, Inc.) provides information and resources for identifying public domain materials. As part of that project, this site has been developed to help users understand what music they can freely use and how they may use it. As the site explains, the rules for public domain use are not as clear-cut as they seem, and users will find a concise and helpful overview of the differences between copyright and public domain, and how to identify and prove public domain. The heart of the site is a 3,000 song alphabetical list of royalty-free music anyone may use in any way. Additional resources at the site include annotated links to other public domain sites and a brief list of examples of projects using public domain music.