Page

The Visualforce page defines the appearance of your user interface using a mixture of
standard HTML and Visualforce-specific XML markup.The XML markup is used to add
view components to the page.View components bind the controller to the page, defining
how data and user actions are to be rendered in the user interface. Force.com provides a
standard set of view components to support common HTML user interface patterns and
supports user-defined components.
In Figure 7-1, the arrows between the page and the controller represent expressions.
Expressions are embedded in view components to allow the page to reference methods in
the controller or in system classes such as UserInfo. Expressions in Visualforce use the
same language as formula fields in the database, with a special prefix and suffix added. For
example, {!save} is an expression that invokes the save method of the controller.



Note
Visualforce maintains a strict separation of business logic and presentation. No business
logic is allowed in a Visualforce page, not even for trivial formatting tasks.