Pexels is an excellent website for free-to-use photos. On the website, anyone can find different kinds of photos for what they need. They include different categories like food, underwater, or backgrounds, so that anyone can find a photo of anything. Regarding the license, which can be found here and here, Pexels says that just about every photo is free to use and in the Public Domain. People can modify the photos, and attribution is not required. However, some of the photos fall under the Creative Commons license, and the use of those photos may still need permission from a third party.