Fair Use is an exception to the exclusive right granted by copyright law to the author of creative work. It permits limited use of copyrighted material without acquiring permission from the rights holders, so long as the final product has a completely different meaning than the original work. The most common cases that would apply in this context are satire and parody, which imply the inclusion of commentary and criticism.
If you plan to pursue a project based on Fair Use of someone else's copyrighted material, please seek professional advice before moving forward. The underlying legal issues are not as simple as they sound in a short summary such as this.