What Is Public Domain

Public domain is any creative work that is free to use in any way.  This includes books, characters, images, movies, etc.

There are four way something becomes public domain.

1. Works that fall into public domain by age is anything created before January 1^st, 1926.  Every year January that beginning date goes up a year. This also know as Public Domain Day.
2. Rights have forfeited.
3. Creator puts it in public domain.
4. It is not suitable for public domain.

Go to Wikipedia, or Copyright Basics: Crash Course Intellectual Property 2 – YouTube and Copyright Term and the Public Domain in the United States | Copyright Information Center (cornell.edu) for more information.