This article is helpful when trying to understand the complexities of US Copyright Law:
http://en.wikipedia.org/wiki/US_copyright
A few parts I found very helpful:
"An important limitation on the scope of copyright protection is the idea/expression dichotomy: While copyright law protects the expression of an idea, it does not protect the idea itself.
The distinction between "idea" and "expression" is a fundamental part of U.S. law, but it is not always clear. From the 1976 Copyright Act (17 U.S.C. § 102):
In no case does copyright protection for an original work of authorship extend 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.
A paper describing a political theory, for example, is copyrightable; it may not be reproduced by anyone else without the author's permission. But the theory itself (which is an idea rather than a specific expression) is not copyrightable. Another author is free to describe the same theory in his or her own words without violating copyright law, and in fact need not even give credit to the original author (although failing to do so may be considered plagiarism, an ethical transgression). Courts disagree on how much of the story and characters of a copyrighted novel or film should be considered copyrightable expression."
"Facts are considered synonymous to "ideas" or "discoveries" under this law and are not copyrightable. By extension, a compilation of uncopyrightable facts is also uncopyrightable... The protection is limited only to the selection and arrangement, not to the facts themselves, which may be freely copied."
I'll edit my post.
