Public Domain

The public domain is an intellectual property designation for the range of content that is not owned or controlled by anyone. These materials are "public property", and available for anyone to use freely for any purpose. ...

Why does PUBLIC DOMAIN exist? It exists to allow the free exchange of knowledge.  If it did not, museums would be allowed to keep images under perpetual copyright, thus denying everyone the opportunity to view, critique, or otherwise examine works. Please note that most 20th century works of art are not yet considered part of the PUBLIC DOMAIN. Click here to view a chart of when works pass into the public domain.

en.wikipedia.org/wiki/Public_domain

a work in the public domain is free for everyone to use without asking for permission or paying royalties. The phrase "public domain" is a copyright term referring to works that belong to the public. ...

www.library.ualberta.ca/guides/plagiarism/terminology/index.cfm

The status of publications, products, and processes that are not protected under patent or copyright. 

library.thinkquest.org/06aug/02220/glossary/index.html

Art, literature, photographs, or music that is available for use by anyone, without cost, because the material has not been copyrighted or because the copyright has expired 

www.mbc.edu/grafton/rpc/glossary.php