|Creative Commons is a system of licensing that was developed as an alternative to the copyright system. Most works that are licensed as Creative Commons are free to use, but many have some sort of catch, such as attribution, no derivatives, or non-commercial use. Make sure you check what sort of CC license your images have.|
Flickr.com has millions of images to search, but be careful! Not all images on Flickr are copyright free. To search for images with Creative Commons licenses, make sure you select "All Creative Commons" from the search menu.
|All images and videos on Pixabay are released free of copyrights under Creative Commons CC0. You may download, modify, distribute, and use them royalty-free for anything you like, even in commercial applications. Attribution is not required.|
|Search for images on the web using Google Image Search. But be careful! Many of the images you find will probably be under copyright.|
In Google Image Search, look for "Usage Rights" under "Search Tools."
Select "Labeled for reuse" or "Labeled for noncommercial reuse" to limit your search to pictures that you can use without being worried about copyright infringement.