An outline is a way of storing, viewing, navigating, and manipulating snippets of text hierarchically.
Outlines are great ways of keeping information readily accessible.
They are also put to many different uses in Frontier. UserTalk scripts are outlines. Menus, which are customizable in Frontier, are represented by outlines. And the database, as represented in the Root Window and its children, is an extended variant of an outline called a table. So you need to be comfortable with outlines in order to do just about anything in Frontier.