Creative Commons helps creators share their work. With a Creative Commons license, you keep your copyright but allow people to copy and distribute your work provided they give you credit -- and only on specificed conditions (e.g. non-commercial, non-derivative, share-alike). Creative Commons is a nonprofit organization that helps overcome legal obstacles to the sharing of knowledge and creativity to address the world’s pressing challenges.
You can use CC-licensed materials as long as you follow the license conditions. One condition of all CC licenses is attribution. This website provides an example of an ideal attribution of a CC-licensed image