One of the most confusing things about photography is when an image is released by the photographer, what can be done with the image? The photographer may feel.. "The image is mine, look but don't touch". A person receiving the image may feel that the image was given to them to "Do anything they want" as long as they don't say that they took the image.
Before I go any further, this post is NOT talking about Copyright, which most understand that the photographer still owns the image unless he/she signs away the rights to the image. The intent of this post is "Hey, I am giving you a copy of my property, this is what you may do with it."
BUT.. You must give me credit for taking the photograph. IF you alter the image, you are STILL required to give me credit for taking the photograph (also known as share-alike, same conditions as the original image).
Attribution- No derivatives
Attribution - Non Commercial
Attribution - Non Commercial, Non Derivative
Of course, any images placed in public domain (Commonly social media), the rights of attribution are waved. Creative commons licensing does not replace any other law, but attempts to make usage clear and simple to all involved. When distributing images professionally or otherwise, it is a great idea to let individuals know EXACTLY what they may do with the image. Of course, more formal licensing commercial licensing agreements exists which include details not specified in CC standards.