"Creative Commons is a nonprofit organization that enables the sharing and use of creativity and knowledge through free legal tools... If you’re looking for content that you can freely and legally use, there is a giant pool of CC-licensed creativity available to you. There are hundreds of millions of works — from songs and videos to scientific and academic material — available to the public for free and legal use under the terms of our copyright licenses, with more being contributed every day"
Creative Commons Search
Offers convenient access to Creative Commons licensed content (images, media, music) provided by search engines and organizations such as Flickr, YouTube, Wikimedia, Google Images, Pixabay, and others