Open licenses are the legal means by which the creators of content can 1) ensure their work is free to access online and 2) grant permission for it to be reused in specific ways while 3) retaining their copyright of the work and 4) getting credit for their original creation.
Open Access licenses are used by authors and artists while Open Source licenses are used by computer programmers and developers.
Creative Commons licenses are the most widely used Open Access licenses. There are different kinds and the licenses exist on a spectrum of openness depending on the restrictions the copyright holder wants to place on reuse of the work. Every license requires that the original creator of the work continue to get attribution and credit.
The infographics below explain how the different Creative Commons licenses compare with one another and what each one allows to be done to the work to which it is assigned.