Openverse (formerly Creative Commons Search) is a great place to start looking for images with a Creative Commons license, which means that they are free to use as long as you attribute them properly. Openverse provides guidance on attribution.
Some common sources for images and photos online are Google Images, Flickr, and Wikimedia Commons. A lot of the content found in these resources is protected by copyright, meaning that you're breaking the law if you use it without permission from the creator. However, there are ways to make sure that you can legally use what you find!
Images from 50+ international cultural heritage institutions, with detailed information and any known licensing restrictions. Most photos have no known copyright restrictions.
For more information about reusing images from Wikimedia Commons, see their guide.
The following resources include stock images and photography of many different subjects.
The following resources lead to diversity-focused collections of stock images and photographs of people.
Free access to over 800,000 images from the The New York Public Library's vast collections, including illuminated manuscripts, historical maps, vintage posters, rare prints, photographs, and more.
Nearly 3 million 2D and 3D images from the Smithsonian Institution's 19 museums, nine research centers, libraries, archives, and the National Zoo.
Books, journals, and other materials on biodiversity from a worldwide consortium of natural history, botanical, research, and national libraries. Provides free access to hundreds of thousands of volumes from the 15th to the 21st centuries.
Free database of over 53,000 images for radiologists, organized by disease, body location, and patient profiles.
Nearly 3 million 2D and 3D images from the Smithsonian Institution's 19 museums, nine research centers, libraries, archives, and the National Zoo.
Gross and microscopic images of pathology specimens. All should have Creative Commons Attribution (CC-BY) licenses.
University of Michigan-Flint