Fair use is an important component of copyright law which provides some flexibility in the use of others' copyrighted material. The provisions of fair use ensure that there are some kinds of uses that do not require permission or payment. Fair use is not a bright line in the law; it is an analysis that must be applied for each use of copyrighted material.
The analysis is based on four factors:
The purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
the nature of the copyrighted work;
the amount and substanitiality of the portion used in relation to the copyrighted work as a whole; and
the effect of the use on the potential market for or value of the copyrighted work.
The resources below explain these concepts further and can step you through a fair use analysis.
Understanding Fair Use -- University of Minnesota Libraries
A thorough discussion of fair use and the factors that are balanced in making a fair use determination.
Thinking Through Fair Use Tool -- University of Minnesota Libraries
A checklist for analyzing whether your use of copyrighted material can be considered fair use.
Code Of Best Practices In Fair Use For Academic And Research Libraries
Developed by the Association of Research Libraries and the Center for Social Media American University the code presents an "easy-to-use statement of fair and reasonable approaches to fair use developed by and for librarians who support academic inquiry and higher education."
Fair Use Checklist -- Columbia University Copyright Office
A checklist to help evaluate whether a specific use of a copyrighted work is a fair use.
The American University Center for Social Media's has developed a series of Fair Use Codes & Best Practices publications addressing fair use considerations from several communities of practice including: