Fair use is a provision of U.S. copyright law that can allow limited use of a copyrighted work without the copyright holder’s permission. It commonly comes up in contexts such as commentary, criticism, teaching, scholarship, and news reporting.

For photographs, fair use is not a blanket exception. It typically depends on the purpose and scope of the use, and whether only a limited portion or a reduced-quality version is used where appropriate. That idea is easy to see with text excerpts; with photos, it can be more nuanced because the whole image is often needed to make the point.

A common example is an educational or reference use, such as illustrating an article that discusses the image itself or the event it depicts. However, whether a specific use qualifies is highly fact-dependent.

Also note that "fair use" is a U.S. legal concept; similar rules vary by country. If there is uncertainty about a planned use, the safest route is to get permission from the copyright holder or seek legal advice.