How Do Copyright Free Images Work?
Some websites allow you to download pictures for private use (e.g. background wallpapers) yet disallow images to be used commercially. This includes instances such as business cards, websites, or posters. The images on the following websites have protection under Creative Commons CC0:
"The person who associated a work with this deed has dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law."—CreativeCommons.org
The following websites either support or are fully composed of CC0 images available in the public domain. The owners of these images have allowed users to modify, edit, and use their images without copyright backlash.