Patents, trade secrets, copyrights and the like are all forms of "intellectual property," though the rules governing each are quite distinct. Patents and trade secrets apply to functional works that are new and innovative. Copyrights, on the other hand, apply to pictorial, textual and sculptural works--works that may not be functional at all. In fact, when an aesthetic creation actually has some functional attributes, problems can arise in obtaining a copyright. Most creative persons will be involved with items which have some aesthetic aspects and, thus, copyrightable features. In order for a work to be copyrightable, it must be original; that is, not copied from anyone else, and it must involve some creativity. The Copyright Statute provides the copyright proprietor with the right to prevent others from copying the protected work. There are several exceptions to this general rule, which characterize copying as permissible even though it is unauthorized. In order to determine whether the unauthorized copying of a copyrighted work is an infringement or a permissible "fair use," it is necessary to evaluate at least four factors. The Copyright Statute states that it is necessary to evaluate: (1) the nature of the work; (2) the nature of the use; (3) the extent of copying; and (4) the effect that the unauthorized copying will have on the copyright owner's market and potential markets. In addition to evaluating these four criteria, the law suggests that other factors may also be relevant. Regrettably, there are no clear-cut answers, and each determination is, at best, a skilled guess.