Anyone can use Public Domain works without obtaining permission, making them ideal for many projects, especially projects that will extend beyond educational uses.
According to Copyright.gov, "A work of authorship is in the 'public domain' if it is no longer under copyright protection or if it failed to meet the requirements for copyright protection. Works in the public domain may be used freely without the permission of the former copyright owner."
You can use Creative Commons-licensed content as long as you correctly attribute the content to its creator and otherwise meet the terms of the license under which the content is offered. Learn more at Creative Commons FAQ.
Watch this brief overview from CreativeCommons.org.
This infographic by adityadipankar introduces the different types of Creative Commons licenses. Learn more about these licenses at CreativeCommons.org.
This guide was adapted from the guide Finding Public Domain & Creative Commons Media with the permission of the creator, Carli Spina, Emerging Technologies and Research Librarian at the Harvard Law School Library.