Fair Use comes from Section 107 in the Copyright Act allows for some uses of copyrighted works without the need for licensing. However, they must fall under the following purposes:
Even if you claim to use it for one of these purposes, it is still possible to lose an infringement case. The court is the one who decides whether something is fair use or not, NOT the user or the author. The court uses a series of guidelines commonly referred to as The Four Factors to determine if something is a fair use or not:
If you take nothing else away from this, know that NOTHING IS GUARANTEED WITH FAIR USE. IF YOU ARE CONSIDERING USING COPYRIGHTED MATERIAL, PLEASE CONSULT LEGAL COUNSEL.