On some sites, new content and content revisions need to be <em>moderated</em>. That is, they need to pass through several <em>states</em> before becoming visible to site visitors. The collection of states and the definition of the transitions between states is known as a <em>workflow</em>. For example, new content might start out in a <em>Draft</em> state, and then might need to pass through several <em>Review</em> states before it becomes <em>Published</em> on the live site.