Paper Space(s) - Layouts and Viewports

The drawing file is organized into multiple visible drawing spaces.  The Paper spaces or Layouts(used synonymously) as they are called are akin to putting a sheet of paper between you and your model. At first you will not be able to see your model until you cut a hole (Viewport) in your paper. You may then scale, zoom and pan the Viewport to display selected portions of your model at different scales.

 

In order for a Viewport to be able to Zoom, Pan, and Scale it must be activated. In order to activate a Viewport you can simply double-click it. Alternately, select the Viewport and click . The border of the Viewport will change from this:

To this:

and the cursor will be constrained to the Viewport. You may then zoom, pan and zoom scale.