Creative Commons is a nonprofit organization that works "to increase the amount of creativity (cultural, educational, and scientific content) in “the commons” — the body of work that is available to the public for free and legal sharing, use, repurposing, and remixing." (http://creativecommons.org/about/what-is-cc).
Creative Commons licenses provide a way for people to share their work and make it available for others to build on and reuse.
Use a Creative Commons License for your own images.
Dianis Matisons, Equestrian sport, 2009, via Flickr
Many students rely upon Google's Image Search to locate images. This is a great strategy, as long as you modify your search slightly so that you identify only images that you can legitimately use. The usage rights filter on the Advanced Search and Advanced Image Search pages shows you pages that are either labeled with a Creative Commons license or labeled as being in the public domain. For images, the usage rights filter also shows you images lableled with the GNU Free Documentation license.
Here are the different usage rights options available:
Flickr contains millions of photographs shared by Flickr users under Creative Commons licenses, and is a strong source for contemporary travel, nature, people, and design photographs.
Several overlays to Flickr offer enhanced search functionality and additional features.
Flickr Creative Commons: Flickr's Creative Commons portal. Browse by license type or choose "Advanced Search" to limit to Creative Commons content.
Behold: Visual search of Flickr photographs. Uses computer vision to recognize visual content, rather than relying on text tags. Limit to "free to use" or "free to modify."
Compfight: Enhanced search of Flickr content. Limit to Creative Commons.
FlickrStorm: Search overlay to Flickr. Retrieves images more images by using related tags. Select "Advanced" to limit to Creative Commons content.
Wylio: Searches only Creative Commons content in Flickr. Additional tools for blogs and websites, including resizing tool, photo credit builder, and code generator.