• ...fair use is a complex doctrine meant to allow certain valuable social purpose
• ...copyright is still violated whether you charged money or not on other's work
• ...almost all things are copyrighted from the moment they are written, and no copyright notice is rigorously required to enforce the author's rights
• ...copyright is not lost because you don't defend it as other Intellectual Property rights (patents, trade marks or industrial design)
• ...facts and ideas can't be copyrighted, but their expression and structure can
• ...one form to make a copyrighted work noticed by its users is (c)
• ...always you should assume for other people's work that is coverd by Copyright law and may not be copied unless you know otherwise