Creative Commons helps you legally share your knowledge and creativity to build a more equitable, accessible, and innovative world. Creative Commons (CC) helps unlock the full potential of the internet to drive a new era of development, growth and productivity. A CC license is used when an author wants to give other people the right to share, use, and/or build upon a work that the author has created. CC provides an author flexibility (for example, they might choose to allow only non-commercial uses of a given work) and protects the people who use or redistribute an author's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work.
Attribution (by): "All CC licenses require that others who use your work in any way must give you credit the way you request, but not in a way that suggests you endorse them or their use. If they want to use your work without giving you credit or for endorsement purposes, they must get your permission first."
ShareAlike (sa): "You let others copy, distribute, display, perform, and modify your work, as long as they distribute any modified work on the same terms. If they want to distribute modified works under other terms, they must get your permission first."
NonCommercial (nc): "You let others copy, distribute, display, perform, and (unless you have chosen NoDerivatives) modify and use your work for any purpose other than commercially unless they get your permission first."
NoDerivatives (nd): "You let others copy, distribute, display and perform only original copies of your work. If they want to modify your work, they must get your permission first."
Licensing Types. Creative Commons.
Image Source: Fotor.com. The Ultimate Image Guide. CC-BY-SA 3.0