Creative Commons provides free tools that let authors, scientists, artists, and educators easily mark their creative work with the freedoms they want it to carry. You can use CC to change your copyright terms from “All Rights Reserved” to “Some Rights Reserved.” I have decided to use “Creative Commons Attribution-Noncommercial-Share Alike 3.0 License”
There is also Creative Commons Search that makes it easier to find Creative Commons-licensed media that you can legally share and reuse for free.
