The law says quite clearly that copyright does not apply to any “idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.” It also doesn’t apply to works that are too short, such as titles, names, etc. and items without a requisite level of creativity, such as lines on notebook paper or even the phone book.
Some things that don’t qualify for copyright protection may qualify for other kinds of protection, such as business names qualifying for trademark protection and inventions qualifying for patents.