Terminology
A screen flow, also known as a dialog, interconnects UI artifacts and guides users through a well-defined sequence of screens. Such dialogs can be composed of multiple steps. A single step is also called a subdialog.
The active step is the subdialog that is active and displayed to the user to work on. In the context of the portal, subdialogs are represented by pages or portlets. Therefore, routing a user from one subdialog to another means redirecting the user from the active step to the next step. The next step then becomes the active step, where each step or subdialog is represented by a page or portlet.
A transition describes how you route a user from one subdialog to another.