Believe it or not, most works fall under Copyright, which means that even if there is no copyright symbol or statement, the image is still covered under copyright. Which also means you may not be able to legally use it in a context other than education (or “fair use.”)
For a guided overview of this topic, see our Copyright Research Guide.
Below are some quick links to sources you can use to find pictures:
Harvard Law School Guide to Finding Public Domain and Creative Commons Images: This guide has a great list of all the places you can go to search for images that you can use that are in public domain.
Creative Commons: This is “a nonprofit organization that enables the sharing and use of creativity and knowledge through free legal tools….and provide(s) a simple, standardized way to give the public permission to share and use…creative work.”
Getty Images: Offers access to over 35 million photographs.
If you have questions regarding copyright and images, please contact the library for assistance.