Do you know about the existence of various types of Creative Commons licenses? Each type of license is explained in the Creative Commons contract.
As it is sometimes difficult to understand the legal terminology, Creative Commons offers simple summaries for each of them. You will find them by selecting the following links:
Attribution 2.5 Generic
Attribution-No Derivative Works 2.5 Generic
Attribution-Noncommercial-No Derivative Works 2.5 Generic
Attribution-Noncommercial 2.5 Generic
Attribution-Noncommercial-Share Alike 2.5 Generic
Attribution-Share Alike 2.5 Generic