Creative Commons (CC) works are works that are still protected by copyright. However, authors have chosen to allow certain kinds of uses--such as being able to copy the work or to share it with others--without the need to seek permission through Creative Commons license agreements.
Creative Commons licensed works can apply to all formats of works.
The best description about the Creative Commons is from its own Web site, "What is Creative Commons?"
Here is a summary of the basic kinds of Creative Commons licenses and the uses that they allow. These definitions are from the "Licenses" page from Creative Commons.
1. Attribution (Abbreviation: BY): This license allows the most kinds of uses. Users may copy, create derivative works, perform, distribute, or display the work without permission; however, users must attribute you as the author in the way that you desire.
2. Non-Commercial (Abbreviation: NC): An author can use this license to ensure that others may use their work, but not make money from using it.
3. No Derivative Works (Abbreviation: ND): This license will allow a user to copy, perform, distribute, or display a work, but they may not create a derivative work. For instance a user may not create a movie based on a book covered under this kind of license.
4. Share Alike (Abbreviation: SA): If you use a work with this kind of license, any derivative work you create must also be covered by the same license.
These four kinds of licenses can be mixed and matched to create a set of use conditions customized to the author's desires.
* Public Domain (Abbreviation: CC0): It is also possible for an author to release their work into the public domain by using this kind of CC license.
If you're looking for Creative Commons (CC) materials, the first resource to consult should be the search engine at creativecommons.org.
Need help attributing a Creative Licensed work? See CC's wiki "Best Practices for Attribution."
Unlike determining whether or not a work is in the public domain, it is a little easier to determine whether or not a work is covered under a Creative Commons license.
There are a few locations on a web site, image, or file to look for the license information.
1. At the bottom of a web page (SAMPLE IMAGE given below from Creativecommons.org):
You will usually see an image like this one with the Creative Commons License abbreviated. You can click on the link for the license to see what you are allowed to do with the material.
2. On the side of a web page (SAMPLE IMAGE given below from stevendepolo's photo: Red Bee Balm Garden on Flickr)
In this case, you would click on the link for "Some rights reserved" in order to see the Creative Commons license information.
3. On an actual document you might see a Creative Commons license where you'd normally see a copyright notice. (SAMPLE IMAGE given below from Lawrence Lessig's 2004 publication, Free Culture (New York: Penguin Press). Lessig released a pdf copy of this book under a Creative Commons license).
4. If you cannot determine whether or not a work is covered by a CC license, then it's likely protected by copyright.