Introduction

Custom components allow custom Visualforce functionality to be encapsulated as discrete modules, which provides two main benefits:

A custom component may have a controller, but unlike Visualforce pages, only custom controllers may be used. A custom component can also take attributes, which can influence the generated markup or set property values in the component's controller.

Custom components do not have any associated security settings; a user with access to a Visualforce page has access to all custom components referenced by the page.