A limited and reasonable use of a copyrighted work (such as quoting a few sentences from a book in a review for that book) without the copyright holder’s permission. Such type of use is not an infringement of the copyright. To determine whether the fair use doctrine provides for a finding of non-infringement, courts consider the following factors: 1. the purpose and character of the use of the copyrighted work, including whether such use was of a commercial nature or was for nonprofit educational purposes; 2. the nature of the subject 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 subject copyrighted work. 17 U.S.C. § 107.
Source: Historical and Revision Notes; House Report: