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." -- Welcome to the Public Domain - Rich Stim      

The timing for when a particular type of format of work enters the public domain varies widely depending on a variety of factors including but not limited to:

•  Unpublished vs. published works
•  Date first published in the U.S.
•  Publications by foreign nationals       
• Publications by U.S. citizens living abroad
• Sound recordings published outside the U.S.     

In the United States, books published in 1927 and films released in 1927 enter the public domain in 2023. Some sound recordings published in 1923 also enter the public domain.