About Public Domain:

Copyrights protect works of authorship, such as writings, music, and works of art that have been expressed tangibly. This also includes movies, video games, videos, software code, choreography, and architectural designs. Currently, works no longer have to be published to be protected and do not require a copyright notice.

For older copyrights, to be "published" or publication meant the distribution of copies or phonorecords of a work (of authorship) to the public by sale, a transfer of ownership or by rental, lease or lending.

Also, the offering to distribute copies or phonorecords to a group of persons for purposes of further distribution, public performance or public display constitutes publication. A public performance or display of a work in and of itself does not constitute publication.

When Copyright Protection Becomes Public Domain

Below is a reference guide that will let you know when you can safely use a piece of art, music or other work without permission because it no longer has copyright protection and has fallen into the public domain as well as how long the copyright protection will last.

Works published prior to 1923: Anything published before 1923 is now in public domain and can be used and distributed freely.

Works published between 1923 and 1963:  If the work in question is published with a © copyright notice or "Copyright [dates] by [author/owner]," it is protected for 28 years and could be renewed again for an additional 67 years for a total of 95 years.

For example, a work copyrighted in 1923 will be in the public domain in 2019. If the work was published without a notice or if the copyright has expired, it is now in the public domain.

Works published between 1964 and 1977: When published with notice, it is copyright protected for 28 years for the first term, with an automatic extension of 67 years for the second term for a total of 95 years.

Works created before 1978, but not published: Copyright notice is irrelevant. Copyright protection lasts for the life of author plus 70 years or until the end of 2002, whichever is later.

Works created before 1978 and published between 1978 and 2002: Copyright notice is irrelevant. Copyright protection lasts throughout the life of author plus 70 years or until the end of 2047, whichever is later. 

Works created in 1978 or after: If the work is fixed in a tangible medium of expression then copyright notice is irrelevant. Copyright protection lasts for the life of the author plus 70 years and is based on the longest living author if the work was jointly created. If it is a work of corporate authorship, done for hire, or anonymous and pseudonymous work, it is protected for 95 years from publication or 120 years from creation, whichever is shorter.