Creators today don't have to do anything to get a copyright; a work that qualifies is automatically fully protected by copyright from the moment it is first "fixed" (meaning, saved in some format, ike a drawing on a chalkboard or whiteboard, or a file saved in a computer's memory). Publication is not a requirement for copyright protection, and even formal registration is purely optional. There is also no requirement to include a copyright notice, date, the "circled c" © symbol, or any other information on the work in order to own a copyright.
Copyright protects original creative expression. Including:
Copyright does not apply to: U.S. Copyright Code, 17 U.S.C. § 102(b)
The public domain is the collection of all expressive works for which no one owns the copyright.
Typically, work enters the public domain in one of two ways: