There is no official definitive answer for whether a use can be considered fair, as every case must be judged on its own merits, but there are some types of use generally allowed under fair use, including criticism and commentary, parody, journalism, education, and research.
Copyright law is not clear on how it uses a fair consideration. It could be difficult to indicate whether someone violates it or not. People second-guess their selves every day on whether they violate it.