For detailed information, consult the Creative Commons website. Here’s a brief summary:
Attribution means: You let others copy, distribute, and display your copyrighted work - but only if they give you appropriate credit. All Creative Commons licenses have this requirement.
Noncommercial means: You let others copy, distribute, and display (and possibly adapt) your work but for noncommercial purposes only.
No Derivative Works means: You let others copy, distribute, and display only identical copies of your work, not translations or other derivative works based upon it.
Share Alike means: You allow others to distribute adaptations, translations, or other derivative works only under a license identical to the license that you chose for your work.