Copyright is a form of protection grounded in the U.S. Constitution and granted by law for original works of authorship fixed in a tangible medium of expression. Copyright covers both published and unpublished works.
-US Copyright Office
The term “public domain” refers to creative materials that are not protected by intellectual property laws such as copyright, trademark, or patent laws. The public owns these works, not an individual author or artist. Anyone can use a public domain work without obtaining permission, but no one can ever own it.
There are four common ways that works arrive in the public domain:
-http://fairuse.stanford.edu/overview/public-domain/welcome/ by Richard Stim
Step 1: Determine whether the work has been published.
FOR PUBLISHED WORKS
1. If it was published before 1924, it's in the public domain
2. If it was published between 1924 and 1989, the law required the copyright holder to process a formal application and to post an official copyright notice. Check to see if a copyright notice is posted on the item. If there is no notice, it's in the public domain. If there is a notice, contact the publisher for permission and post "In Copyright."
3. If the item was published after 1989, you must seek permission from the publisher to post the item. Make sure to secure written permission.
FOR UNPUBLISHED WORKS
1. Copyright applies at creation and lasts for the term of the original creator's life plus 70 years. Seek permission from the current copyright holder, which may be the family of the original creator. Post only with permission and be sure to note that the work is "In Copyright."