Field sets combine the power of Visualforce to create custom user interface pages with what has always been a defining trait of the Force.com platform: the ability for administrators to customize the application using config over code.

A field set is a grouping of fields. For example, you could have an account search Visualforce page that uses a field set to control which account fields are returned in the search results. When a field set is added to a Visualforce page, developers can loop over its fields and display them. The same Visualforce page can therefore be used to present a different set of information, depending on which fields you wish to render.

Field sets enable you to customize the fields that appear on a custom Visualforce page using a simple drag-and-drop interface to add, remove, or rearrange fields from the field set without altering the Visualforce page, as shown in the following screenshot:

When a field is included in the Available for the Field Set section, it exists in the field set, but it will not be rendered on the Visualforce page. You can display the field by moving it from the Available for the Field Set column to the In the Field Set column.

When a field is marked as In the Field Set, the field will be rendered on the Visualforce page. You can remove the field from the page by removing it from the In the Field Set column.