To download and share digital content legally and  let people know that you want them to reuse your own work, creative commons licenses can help you do both when something like a photograph or a sound track is created, it is automatically protect by copyright, you may always get the permission of sharing and reusing their work.

Creative commons licenses elements:

-you must acknowledge the author and contain their work when you publish your work

-the author is the only person who can make money from their work

-you must get the permission before retouching or mixing up the original creation

Click here to view the more specific content about the licenses:

http://creativecommons.org/licenses/?lang=en