A Control is a UI element that can be added to a 
Page, such as text boxes, data fields and tables.
Each Control represents an HTML structure that is added to the Page when written to a browser.
The WYSIWYG View in the Form editor shows the current browser view of a Page's Controls.
You add a Control to a Page by dragging it from the 
Palette to either the Outline View or the WYSIWYG View. Each Control can be added to a Page any number of times.
Container Controls are a class of Control that accept child Controls and allow you to build up complex structures of Controls.
Contols take their style (their size, colour, etc) from the 
Theme associated with their owning 
Form. Each instance of a Control that is added to a Page can be further styled to suit its purpose in the Page.