Creative Commons is a global nonprofit organization that enables sharing and reuse of creativity and knowledge through the provision of free legal tools.
Creative Commons licenses are copyright licenses, and depend on the existence of copyright to work.
Creative Commons licenses are legal tools that creators and other rights holders can use to offer certain usage rights to the public, while reserving other rights. Those who want to make their work available to the public for limited kinds of uses while preserving their copyright may want to consider using Creative Commons licenses. Others who want to reserve all of their rights under copyright law should not use Creative Commons licenses.
(Source: Creative Commons FAQ)
How do I find openly licensed material?
Openly licensed material can be found in abundance on the web:
Types of licenses, ranging from the most freeing to the most restrictive. The most free license is attribution. This license lets you distribute, remix, tweak, and build upon the original work, even commercially, as long as you credit the original creation. This is the most accommodating of licenses offered. The attribution-sharealike license is the next freest which lets you remix, tweak, and build upon the original work even for commercial purposes, as long as you credit the original work and license your new creations under the identical terms. The license is often compared to copyleft free and open source software licenses. All new works based on the work should carry the same license, so any derivatives will also allow commercial use. This is the license used by wikipedia. This is followed by the attribution-noderivs license which allows for the redistribution, commercial, and non-commercial, as long as it is passed along unchanged and in whole, with credit to the original work. More restrictive is the attribution-noncommercial-sharealike license. This license lets you remix, tweak, and build upon the original work non-commercially, as long as you credit the original work and license your new creations under the identical terms. The most restrictive license is attribution-noncommercial-noderivs. This license only allows you to download the original work and share it with others as long as you credit the original work. You can't change the original work in any way or use it commercially.
Image credit: "How To Attribute Creative Commons Photos" by Foter via University of British Columbia, used under Creative Commons Attribution-ShareAlike 3.0 Unported license.
Oakland Community College Library Research Guide on Open Educational Resources by OCC Librarians is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Based on a work at http://nmc.libguides.com/oer/home and https://libguides.lcc.edu/oer/overview.