As you navigate documents in the outline, a play mode toolbar appears when you select a topic document. It displays several buttons for running application simulations in any of the following modes, depending on what your content publisher has made available: 

Note: You can also double-click a topic to launch it in the default play mode.

In addition to playing topics in these modes, the content you are viewing may also include questions and/or assessments that test your knowledge of the content. Question and assessment content always appears in the Concept pane as opposed to topic playback which appears in a new window. Sections and topics may also display conceptual information.