Wikipedia Basics

Before you upload an image, make sure that the image falls in one of the four categories:

• Own work: You own all rights to the image, usually meaning that you created it entirely yourself. (example)
• Freely licensed: You can prove that the copyright holder has released the image under an acceptable free license. Note that images that are licensed for use only on Wikipedia, or only for non-commercial or educational use, or under a license that doesn't allow for the creation of modified/derived works, are unsuitable. (example) When in doubt, do not upload copyrighted images.
• Public domain: You can prove that the image is in the public domain, i.e. free of all copyrights. (example)
• Fair use: You believe that the image meets the special conditions for non-free content, which exceptionally allow the use of unlicensed material, and you can provide an explicit non-free use rationale explaining why and how you intend to use it. (example)

Here are my top picks for finding public domain and freely licensed images.