By definition, Creative Commons is ” a nonprofit organization that works to increase the amount of creativity (cultural, educational, and scientific content) available in “the commons” — the body of work that is available to the public for free and legal sharing, use, repurposing, and remixing.”
Creative Commons Licenses provide a standard way for user-generated content creators to grant someone else permission to use their work, in other words, a Creative Commons license is used when the authors want to give others the rights to share, use , or build upon the work they have created.
This beautiful graphic by adityadipankar. sums up the poignant points you and your students need to know to better understand CC. Check it out from this page.