Copyright law and "Fair Use"

[Atreyu]

I’ve seen the term “fair use” used on this board, and I’m hoping to get an exact clairification. I know that since this message board is owned by the Chicago Reader newspaper, the issue of copyright violations is taken very seriously here. Can anyone tell me what exactly does “fair use” mean under copyright law, and what it entails?

[Measure_for_Measure]

This is a nice essay:
http://www.templetons.com/brad/copymyths.html

This is a website devoted to copyright and fair use:

Home

[RealityChuck]

Fair use is ultimately determined by the following guidelines:

§ 107. Limitations on exclusive rights: Fair use
Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include—
(1) the purpose and character of the use, including whether such use is of a
commercial nature or is for nonprofit educational purposes;
(2) the nature of the copyrighted work;
(3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
(4) the effect of the use upon the potential market for or value of the copyrighted work.
The fact that a work is unpublished shall not itself bar a finding of fair use if such
finding is made upon consideration of all the above factors.

[Exapno_Mapcase]

Unfortunately, in the real world, the only precise meaning of “fair use” is “that part of the copyright law that causes people to tear their hair out trying to come up with a precise meaning.”