Copyright can be confusing. Use the tools on this page to help you work through copyright issues in what you use in your classes.
Creative Commons doesn't replace copyright, it is stands on copyright law and offers additional types of permissions. In most cases, material retains its copyright for 95 years from publication or 120 years from creation whichever is shorter. Or if we know the identity of the author, the term is the author's life plus 70 years. Creative Commons materials retain their license in perpetuity and cannot be revoked.
Public domain, of course, no longer has a copyright on it.
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License
Professor Eric Faden of Bucknell University created this humorous, yet informative, review of copyright principles delivered through the words of the very folks we can thank for nearly endless copyright terms.