This document summarizes Creative Commons and how it provides a standardized way for creators to grant copyright permissions to their creative works through flexible licensing options. It explains the four main license conditions creators can choose from (Attribution, ShareAlike, NonCommercial, NoDerivatives) and the CC0 public domain dedication. It provides examples of how works can be properly marked up with machine-readable Creative Commons metadata and licenses. Over 550 million items are licensed under Creative Commons, covering various topics and media types.