Openverse Free-to-Use Media
The official WordPress webite isn’t just a place where you can find free plugins (like the ones I write about in the Toolbox WordPress section) and themes; it also happens to be the home of the Openverse online catalogue of free-to-use media: images and audio.
According to them, they have over 600 million items you can pick through and use at no cost. Just enter a keyword, select the type of content you’re looking for, and it shows you what it has. Download and use what you want for your website, blog, etc.
Very important to note: These are NOT all public domain (aka copyright-free) images and sound clips. A lot of them are open source, meaning their producers wish to retain copyright, but make the media available for use for free, but with Creative Commons License restrictions in place, depending on which of the CC licenses they choose to use.
The specific CC restrictions in effect are listed with each media item. The need to credit the creator is typical. Some disallow commercial use and/or modifications. Things like that.
Here’s an example. A picture of a penguin. Because, why not? Click on it to see the image in its original modest resolution of 768×1024 (there are many images there at much higher resolutions). Also note the caption, which complies with what its CC license requires for its use.