The content in wiki is licensed under a free culture Creative Commons license -
CC BY-SA 4.0 
Creative Commons (CC) is an American non-profit organization devoted to expanding the range of creative works available for others to build upon legally and to share - wikipedia
The organization has released several copyright-licenses known as Creative Commons licenses free of charge to the public. These licenses allow creators to communicate which rights they reserve, and which rights they waive for the benefit of recipients or other creators.
An easy-to-understand one-page explanation of rights, with associated visual symbols, explains the specifics of each Creative Commons license.
Creative Commons licenses do not replace copyright, but are based upon it. They replace individual negotiations for specific rights between copyright owner (licensor) and licensee, which are necessary under an "all rights reserved" copyright management, with a "some rights reserved" management employing standardized licenses for re-use cases where no commercial compensation is sought by the copyright owner.
The result is an agile, low-overhead and low-cost copyright-management regime, profiting both copyright owners and licensees. Wikipedia uses one of these licenses.
The organization was founded in 2001 by Lawrence Lessig, Hal Abelson, and Eric Eldred with the support of Center for the Public Domain. In 2002 the Open Content Project, a 1998 precursor project by David A. Wiley, announced the Creative Commons as successor project and Wiley joined as CC director. Matthew Haughey and Aaron Swartz also played a role in the early stages of the project.
As of January 2016 there were an estimated 1.1 billion works licensed under the various Creative Commons licenses. As of March 2015, Flickr alone hosts over 306 million Creative Commons licensed photos.
# See also