The U.S. Copyright laws initially were created to "Promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries" (United States Constitution, Article I, Section 8).
Once a work becomes tangible (that it, it is saved as a document, art work, sculpture, film, sound byte, etc.), it is copyrighted. Formal copyright registration enhances the legality of creative work's ownership. Ideas are not copyrighted until they are written down. Facts and slogans cannot be copyrighted.
According to 17 U.S.C. § 102, copyrighted works include:
Digital Rights Management (DRM) is a system that encrypts electronic data so that it can only be accessed by authorized users. This method of "digitally watermarking" resources protects creators' intellectual property from being accessed and shared freely among Internet users.
Scholarly articles that are protected by DRM cannot be saved and emailed; rather, each person who needs a specific article must access it individually.