A Quick Guide to Understanding Creative Commons Licenses
Attribution (CC BY): Requires the user to attribute the source of the work; all other uses are allowed.
Attribution / Non-Commercial (CC BY-NC): Requires the user to attribute the source of the work. The user is permitted to change the work, but may not use it for commercial purposes.
Attribution / ShareAlike (CC BY-SA): Requires the user to attribute the source of the work. The user is allowed to make changes to the work, but any derivative works must also be released under a CC BY-SA license.
Attribution / Non-Commercial / ShareAlike (CC BY-NC-SA): Requires the user to attribute the source of the work. The user is allowed to make changes to the work, but may not use it for commercial purposes, and any derivative works must also be released under a CC BY-NC-SA license.
Attribution / Non-Derivative (CC BY-ND): Requires the user to attribute the source of the work, but prohibits the user from making any changes to the work.
Attribution / Non-Commercial / Non-Derivative (CC BY-NC-ND): Requires the user to attribute the source of the work, and prohibits the user from making any changes to the work or using it for commercial purposes.
For more information about sharing your work, see the Creative Commons tool for choosing a license.