Fair Use is a very grey area and this is on purpose. Here is a list of four criteria in determining Fair Use.
The easiest way to ensure you aren't breaking copyright is to simply get permission to use it.
If you are using it to comment, criticize, or parody the work, it falls under fair use.
Not Fair Use:
Remember that every country has it's own version of Fair Use. The version you should use is the version from the country of the works origin.
Things that do not make something Fair Use: