Public Domain: The public domain is not a place. A work of authorship is in the “public domain” if it is no longer under copyright protection or if it failed to meet the requirements for copyright protection. Works in the public domain may be used freely without the permission of the former copyright owner. (from: https://www.copyright.gov/help/faq-definitions.html)
Founded in 2011, The Public Domain Review is an online journal and not-for-profit project dedicated to the exploration of curious and compelling works from the history of art, literature, and ideas.