A public domain work is a creative work that is not protected by copyright and which may be freely used by everyone.
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Works fall into the public domain for four main reasons:
1. the term of copyright for the work has expired;
2. the author consciously chose not to protect his work with a copyright;
3. the author failed to satisfy statutory formalities to perfect the copyright, or
4. the work is a work of the U.S. Government.
As a general rule, most works enter the public domain because of old age. This includes any work published in the United States more than 95 years ago. Another large block of works are in the public domain because they were published before 1964 and copyright was not renewed. (Renewal was a requirement for works published before 1978.) A smaller group of works fell into the public domain because they were published without copyright notice (copyright notice was necessary for works published in the United States before March 1, 1989).
Use the Copyright Slider Tool to determine if a work is still protected by copyright.
Many public domain resources can be found on the web.
Books
Music
Texts, Video, and Audio