Creative Commons (CC) is a nonprofit organization. CC has developed a series of licenses that provide opportunities for creators and owners of copyrighted works to more easily share their creative works under a licensing framework, thus substantially avoiding copyright questions in many circumstances.
The various CC licenses in essence functionally "pre-define" how a user of the work can make copies, distribute, perform and make other uses without analyzing the copyright implications of those uses. The CC license come in many flavors and address legal, technological, and lay perspectives in their language and structure.
Educators and others are increasingly attaching CC licenses to certain works requiring only that the user provide attribution in using the work. Thus, the user may use the work in many important and diverse ways by simply providing information about the creator of the work.