A scaffold is a special page containing a form that can be filled in and submitted in one step. This allows you to rapidly create a page using the content entered.
The form that makes up a scaffold is defined by a dialog definition, just like a normal dialog, though it appears on the scaffolding page in a different form. Because dialog definitions are used to define scaffolds, scaffolds can be designed using the dialog editor. Note that when using the dialog editor in this fashion, the render pane will still display the the dialog definition in the form of a dialog box not as a scaffold.
See Scaffolding for more information on using the dialog editor to create scaffolds.