Creative Commons licenses are free, easy-to-use copyright licenses that provide a standardized way to give permission to share and use your creative work.
From the Creative Commons site: "Creative Commons licenses are legal tools that help you grant copyright permissions to the general public. Our CC legal tools include six different licenses and one public domain dedication tool. It is important to specify which one of the 7 legal tools you are applying to your material. CC licenses may be applied to any type of copyrightable work. The only types of works for which CC does not recommend its licenses are computer software and hardware, where we recommend a standard free software license instead. For works that are already in the public domain we recommend that you mark them with the Public Domain Mark. If you hold the rights to a work but would like to place it into the public domain, you can use the Chooser to select CC0."
There are six CC license options. To determine which one is most suitable for you, consider the following questions:
Adapted from:foter, CC BY-SA 3.0, via Wikimedia Commons
If you need help with choosing an appropriate CC license, you can make use of this Creative Commons License Chooser to guide your decision.