Creative Commons is a form of licensing developed by the Creative Commons Foundation, which aims to facilitate free sharing of creative works within limits specified by the license terms.

CC licenses are modular and the following components may be mixed and matched to achieve a variety of different terms:

• Attribution (BY): Licensees may copy, distribute and display
  the work and make derivative works based on it only if they give the
  author a credit as specified by the licence.
• Noncommercial l (NC): Licensees may copy, distribute and display the work and make derivative works based on it only for non-commercial purposes.
• No Derivative Works(ND): Licensees may copy, distribute and display  only exact copies of the work, not derivative works based on it.
• ShareAlike (SA): Licensees may distribute derivative works only under a license identical to the license that governs the original work. 

EG a BY-NC-ND licence would permit only bylined, non-commercial  copying but no derivative works. Omitting the byline or commercial use or making derivative works would break the terms of the license and would be actionable.

CC licenses are not without problems, both real and potential:

• Their complexity discourages people from reading or understanding exactly what the licence permits. CC is often assumed to mean much the same as free of copyright by image users, and that misunderstanding can encourage infringements.
• Despite CCF taking care to formulate terms that are in theory valid in many different countries there have been very few instances where the courts have tested their enforceability.
• Once an image has been released with a .'liberal' licence it is practically impossible to revert the terms to more restrictive permissions.
• Unforeseen outcomes may occur. For instance, if an image is released for non-commercial use and is then used by a non-profit site for purposes.that the author deplores yet finds his name alongside. As the license terms have been complied with there is nothing the photographer can do.

It is hard to see any benefit of CC licensing applied to photographs compared to traditional retention of full copyright. The latter does not preclude free usage or sharing, it just means the author's consent must be obtained,. The photographer therefore retains full control of how, by whom, where and for how much money.