Like any other resource, images are generally protected by copyright. For more on copyright and fair use, visit our Copyright Basics Guide.
Images can also be licensed under Creative Commons, which allows for a standardized way to grant the public permission to use creative work under copyright law. There are six different types of CC licenses, which are detailed on the "About CC Licenses" webpage. For help determining which Creative Commons license you'd like to use, or for any Creative Commons questions, please reach out to Anna at email@example.com.
Even if the image you're using is in the public domain, it's still good practice to cite it. Just as you would cite information that you use from an academic journal article, book, or other information source, so should you cite your images. Please make sure to check the individual style guide that your professor has asked you to use (like MLA, Chicago Manual of Style, or APA).
Generally when citing images, here is the information that you should include:
Here's an example of an image citation using Chicago Manual of Style:*
Lewis W. Hine, In an Old-Fashioned Textile Mill (Spinner), 1912, gelatin silver print, 5 x 6 15/16 in., Getty, Los Angeles, CA, https://www.getty.edu/art/collection/object/106RJ4#full-artwork-details.
*Please note that the text spacing and indentation may not represent what's required in CMoS; always double check with the manual.*