2. How does Fair Use fit with Copyright Law?
Copyright law embodies a bargain: Congress gave copyright holders a set of six exclusive rights for a limited time period, and gave to the public all remaining rights in creative works. The goals of the bargain are to give copyright holders an economic incentive to create works that ultimately benefit society as a whole, and by doing so, to promote the progress of science and learning in society. Congress never intended Copyright law to give copyright holders complete control of their works. The bargain also ensures that created works move into "the public domain" and are available for unlimited use by the public when the time period finishes. In addition, as part of the public's side of this bargain, U.S. Copyright law recognizes the doctrine of "fair use" as a limitation on copyright holders' exclusive right of reproduction of their works during the initial protected time period.

The public's right to make fair use of copyrighted works is a long-established and integral part of US copyright law. Courts have used fair use as the means of balancing the competing principles underlying copyright law since 1841. Fair use also reconciles a tension that would otherwise exist between copyright law and the First Amendment's guarantee of freedom of expression. The Supreme Court has described fair use as "the guarantee of breathing space for new expression within the confines of Copyright law".

3. How Do You Know If It's Fair Use?
There are no clear-cut rules for deciding what's fair use and there are no "automatic" classes of fair uses. Fair use is decided by a judge, on a case by case basis, after balancing the four factors listed in section 107 of the Copyright statute. The factors to be considered include:

The purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes — Courts are more likely to find fair use where the use is for noncommercial purposes.
The nature of the copyrighted work — A particular use is more likely to be fair where the copied work is factual rather than creative.
The amount and substantiality of the portion used in relation to the copyrighted work as a whole — A court will balance this factor toward a finding of fair use where the amount taken is small or insignificant in proportion to the overall work.
The effect of the use upon the potential market for or value of the copyrighted work — If the court finds the newly created work is not a substitute product for the copyrighted work, it will be more likely to weigh this factor in favor of fair use.
4. What's been recognized as fair use?
Courts have previously found that a use was fair where the use of the copyrighted work was socially beneficial. In particular, U.S. courts have recognized the following fair uses: criticism, comment, news reporting, teaching, scholarship, research and parodies.