Fair Use is addressed in 17 U.S. Code § 107. The official language is as follows:
In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include—
A few points of expansion on the text given in copyright law...
Purpose and character of the use
Nature of the copyrighted work
Amount and substantiality of the portion used in relation to the copyrighted work as a whole
Effect of the use upon the potential market for or value of the copyrighted work
1. U.S. Copyright Office, "More Information on Fair Use," last modified March 2019, https://www.copyright.gov/fair-use/more-info.html
In order to help you determine if your use qualifies as Fair Use, please use the following checklist courtesy of Columbia University Libraries.
The Checklist is licensed by a Creative Commons Attribution License with attribution to the original creators of the checklist Kenneth D.Crews (formerly of Columbia University) and Dwayne K. Buttler (University of Louisville). Retrieved from https://copyright.columbia.edu/basics/fair-use/fair-use-checklist.html