Public domain works are not protected by intellectual property laws such as copyright, trademark, or patent laws. The country where the book was first published determines the applicable copyright law to apply to the work. Works are generally considered public domain if:
- the copyright has expired
- the copyright owner deliberately places it in the public domain, known as "dedication"
- copyright law does not protect this type of work
As of 2022, works originally published in the United States in and before 1926 are considered to be in the public domain.
In the United States:
For works published after 1977:
- if written by a single author, the copyright will not expire until 70 years after the author's death.
- If written by several authors, it will not expire until 70 years after the last surviving author dies.
Differentiated works are unique and meet one or more of these requirements:
- Translated: Unique translations
- Annotated: Unique additional content such as footnotes, study guides, or literary critiques
- Illustrated: 10 or more unique illustrations relevant to the book
Books that meet these requirements must include (Translated), (Annotated), or (Illustrated) in the title. For example, "Alice in Wonderland (Illustrated)" may be acceptable under copyright law, but you should also confirm whether the title is currently trademarked and whether your title violates the trademark registration. The book description must also include a summary of how the book is unique.
Only the copying of the original public domain work is permitted.