Stanford University Libraries have exceptional resources related to copyright and fairuse. The information noted below is from their site and used with permission of a Creative Commons Attribution-Non Commercial 3.0 License. Click on the article title in each section to read more.
Copyright protects works such as poetry, movies, CD-ROMs, video games, videos, plays, paintings, sheet music, recorded music performances, novels, software code, sculptures, photographs, choreography and architectural designs.
To qualify for copyright protection, a work must be “fixed in a tangible medium of expression.” This means that the work must exist in some physical form for at least some period of time, no matter how brief. Virtually any form of expression will qualify as a tangible medium, including a computer’s random access memory (RAM), the recording media that capture all radio and television broadcasts, and the scribbled notes on the back of an envelope that contain the basis for an impromptu speech.
In addition, the work must be original — that is, independently created by the author. It doesn’t matter if an author’s creation is similar to existing works, or even if it is arguably lacking in quality, ingenuity or aesthetic merit. So long as the author toils without copying from someone else, the results are protected by copyright.
Finally, to receive copyright protection, a work must be the result of at least some creative effort on the part of its author. There is no hard and fast rule as to how much creativity is enough. As one example, a work must be more creative than a telephone book’s white pages, which involve a straightforward alphabetical listing of telephone numbers rather than a creative selection of listings.
ABSOLUTELY FREE! MUSIC, TEXT, AND ART!! COPY ALL YOU WANT!! If you saw an advertisement like this, you might wonder, “What’s the catch?” When it comes to the public domain, there is no catch. If a book, song, movie, or artwork is in the public domain, then it is not protected by intellectual property laws (copyright, trademark, or patent laws)—which means it’s free for you to use without permission.
As a general rule, most works enter the public domain because of old age. This includes any work published in the United States before 1923 or works published before 1964 for which copyrights were not renewed. (Renewal was a requirement for works published before 1978.) A smaller group of works fell into the public domain because they were published without a copyright notice, which was necessary for works published in the United States before March 1, 1989. Some works are in the public domain because the owner has indicated a desire to give them to the public without copyright protection.
In its most general sense, a fair use is any copying of copyrighted material done for a limited and "transformative" purpose such as to comment upon, criticize or parody a copyrighted work. Such uses can be done without permission from the copyright owner. Another way of putting this is that fair use is a defense against infringement. If your use qualifies under the definition above, and as defined more specifically in this section, then your use would not be considered an illegal infringement.
So what is a "transformative" use? If this definition seems ambiguous or vague, be aware that millions of dollars in legal fees have been spent attempting to define what qualifies as a fair use. There are no hard-and-fast rules, only general rules and varying court decisions. That's because the judges and lawmakers who created the fair use exception did not want to limit the definition of fair use. They wanted it--like free speech--to have an expansive meaning that could be open to interpretation.
Most fair use analysis falls into two categories: commentary and criticism; or parody.
1. Comment and Criticism
If you are commenting upon or critiquing a copyrighted work--for instance, writing a book review -- fair use principles allow you to reproduce some of the work to achieve your purposes. Some examples of commentary and criticism include:
The underlying rationale of this rule is that the public benefits from your review, which is enhanced by including some of the copyrighted material. Additional examples of commentary or criticism are provided in the examples of fair use cases.
A parody is a work that ridicules another, usually well-known work, by imitating it in a comic way. Judges understand that by its nature, parody demands some taking from the original work being parodied. Unlike other forms of fair use, a fairly extensive use of the original work is permitted in a parody in order to "conjure up" the original.