Copyright laws require permission to be granted before someone can reuse a copyrighted work, whether written, visual, or audio. Getting permission can be time-consuming and frustrating.
Creative Commons licenses allow people to grant preemptive permission for reuse of their work. A Creative Commons license tells you what you can do with a work without asking, and what you can't do.
The sites below contain images of many kinds that are licensed either to the public domain or for reuse under a Creative Commons license. They may also contain images that retain more strict copyright, so look closely before reusing anything.