Books, Articles, Photographs, Poems, Plays, Songs, and more...
"...including literary, dramatic, musical, artistic, and certain other intellectual works. This protection is available to both published and unpublished works" (U.S. Copyright Office, Copyright Basics).
Works must be:
FIXED - that is, fixed in a tangible medium, like a piece of paper or video recording: an idea alone cannot be copyrighted.
ORIGINAL - though it is not necessary for a work to be completely original: existing works may be combined, adapted, or transformed in new ways that make them eligible for copyright protection.
MINIMALLY CREATIVE - and only a slight degree of creativity is all that is required to be eligible for protection.
Forms, Facts, Names, Slogans, Words, Ideas, plus certain types of works: