Images from sources listed here are free for all non-commercial use, meaning you can include them in projects created for personal or educational purposes. Most of them are in the public domain (no copyright because of age) or distributed under Creative Commons licenses.
Always read and comply with the use restrictions for specific image sources, and remember to cite images someone else created.
Start your search with Openverse, a search tool that includes millions of open access images from sources including Flickr, Wikimedia Commons, and the Smithsonian.
Each site (and sometimes, each photo) has different restrictions. Be sure to check before you choose an image!
Creative Commons licenses provide a way for people to share their work and make it available for others to build on and reuse.