Some online sources of free images and illustrations include Free Images, Wikimedia Commons, Flickr: The Commons, MorgueFile, StockVault and Picdrome. The United States federal government website also contains numerous images that are available for free to the public.
The World Wide Web hosts a vast number of public domain resources that offer stock photography. Images in the public domain are copyright-free photos that provides unlimited access to users, such as those at Picjumbo, PD Photo, Pixabay and Liam's pictures from Old Books.
Other websites also offer a collection of free images and illustrations with certain restrictions and usage rights. The pictures at WorldImages can only be used for educational and non-profit purposes, while images at deviantART are both free and copyrighted material.