One of the most commonly misunderstood concepts in copyright law that I encounter is fair use. It should be said at the outset that you cannot just take content that is on the internet and use it for your own purposes because of "fair use." Fair use is a very murky area with a lot of legal concepts that you should consult a lawyer about before using any materials you believe may still be protected under copyright. Also, the mere fact that you are a nonprofit or an educational institution does not insulate you from copyright infringement under fair use. Fair use is an affirmative defense to copyright infringement and there are four factors that the copyright statute says are relevant to whether something is a fair use of a copyrighted work:
1. Commercial or NonCommercial Purpose
2. Nature of the Copyrighted Work
3. The Amount Taken
4. Economic Impact.
None of these factors is dispositive - they are all interrelated and some factors may be weighed more by a court than others. In addition, a court will often look to see if a use is transformative, that is, does the fair use change the original work enough to merit its own protection. As you can see, this is a very muddy area of law, with the Supreme Court even having trouble articulating the concepts so you really want to tread carefully before relying on fair use as a defense.