Pixabay is a great site if you’re looking for copyright free, royalty-free images to use in your projects.
Started by two Germans who got frustrated trying to find good images for free online, it’s quickly become one of the top image sites online.
Literally, based on buying contributors a “cup of coffee” (eg. donations), many people can’t seem to believe the images are free, being released under a CC0 (Creative Commons Zero) license which is essentially the same as making them “public domain” under conventional understanding of copyright.
If you work for a library (where our entire business model is based on essentially putting material that would otherwise be considered copyrighted freely available into the public domain), it’s great to see sites like this making useful information available for free to anyone who wants it.