The purpose of copyright law is to promote the progress of useful arts and science by protecting the exclusive right of authors and inventors to benefit from their works of authorship. To this end, the US Copyright Act of 1976 -a complete revision of the Copyright Act of 1909- protects all the works of authorship created between 1978 and the present. This protection extends to works that are unpublished but are in a fixed and tangible form. Copyright law is regulated by the federal government by registering copyrighted works through the Copyright Office (a division of the Library of Congress) and by enforcing copyright laws in the federal court system.

The most commonly litigated issue in copyright law involves copyright infringement. Disputes regarding the violation of any exclusive right granted under copyright law, such as copying a work, are filed in federal courts due to Federal Preemption.

Copyright law protects literary, musical, graphic, or other artistic forms in which an author expresses intellectual concepts. In the context of copyright law an author is the creator of any copyrightable creation. Any author creation that meets the standards of copyright law is protectible under copyright law and considered to be a work of authorship. The main two requirements to meet the standards of copyright law are originality and fixation.

References:
[1] Stim, R. "Intellectual Property. Patents, Trademarks, and Copyrights" West Legal Studies.
[2] Black's Law Dictionary 5th ed., (West Publishing, 1979).