Through the Internet we now have near universal access to a vast quantity of informational, educational, cultural, and other knowledge. Copyright law was created before any of this existed and has yet to catch up. When digital content is posted to the internet, there is a reasonable expectation that the content will be shared, downloaded, possibly modified, and re-posted. But technically, any action we take with anyone else's creative property (digital or not) may be considered infringement.
Creative Commons lends a flexibility to copyright that is not written into the law. Creative Commons provides licenses that work alongside copyright allowings creators of original work to share their work in a way that best suits their needs. For more information about the philosophy behind Creative Commons and how to use Creative Commons-licensed work, check out this video:
Attribution - This license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation.
Attribution-ShareAlike - This license lets others remix, tweak, and build upon your work even for commercial purposes, as long as they credit you and license their new creations under the identical terms.
Attribution-NonCommercial - This license lets others remix, tweak, and build upon your work non-commercially; new works must also acknowledge you and be non-commercial, but they don’t have to license their derivative works on the same terms.
Attribution-NonCommercial-ShareAlike - This license lets others remix, tweak, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms.
Attribution-NonCommercial-NoDerivs - This license is the most restrictive of our six main licenses, only allowing others to download your works and share them with others as long as they credit you; works cannot be changed or used commercially