An Action records a human activity that changes or copies a page. Actions are of a small number of types that apply to all pages and their items.
Actions of type 'create' indicate newly made pages.
Actions of type 'add', 'delete' and 'move' arrange the story.
Actions of type 'edit' change the contents of a story item.
Actions of type 'fork' change the ownership of a page.
The Journal, when properly maintained, collects the complete history of a wiki page.