A creative commons license allows creators to copyright their work while allowing others to use, edit, and distribute it at the same time, given that they are properly credited.
There are 6 types of creative commons licenses:
Allows commercial and non-commerical distrubution and editing/tweaking so long as it is credited.
Allows commercial editing/addition to your work so long as editors license their new creations under identical terms.
Allows commercial and non-commercial distribution so long as the work remains complete, unchanged and is credited.
Allows non-commercial editing/addition to the work so long as it is credited.
Allows non-commercial editing/addition to the work so long as it is credited and licensed under identical terms.
Allows others to only download work (no editing whatsoever) and share with others so long as it is credited.