"The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because no one holds the exclusive rights, anyone can legally use or reference those works without permission." ¹
The Public Domain Review open_in_new: Curious and compelling out-of-copyright works from the history of art, literature, and ideas.
Duke Law Center for the Study of the Public Domain open_in_new: Even more explanations and free to use old goodies.
Got more hubs of public domain content? Let me know! I'll add them here.