Creative Commons is a way to document and communicate the licensing agreements for someone who owns the copyright of a resource and wants others to be able to use it.
A description of the levels of licensing is available at http://creativecommons.org/licenses/. This provides a list of the license levels and what the permissions are for accessing the material, and using it in your work. You can use it in your work, modify the work and thereby creating a new piece of work, and this can be for either commercial or non-commercial purposes.
Public domain – is a state where the item is available to the public.