This is about how we can use Field Set. We can dynamically bind fields on our visual force page using Field Set. It is very useful when we are working with managed package.
A field set is a grouping of fields. For example we can have a field set that contains fields "Name , Email , Phone , Mobile". If the page is added to a managed package, administrator can add, remove, or reorder fields in a field set to modify the fields presented on visual force page without modifying any code. Creating a field set : Go to Setup > App Setup > Create > Objects > Select your object > Field Set (Beta) > New :
Fields in "In the Field Set" section is displayed on visual force page and administrator can add more fields in "In the Field Set" from "Available for the Field Set" section.
Visual Force Page Code :
Now it will show three fields (Name, Email, Mobile) on visual force page, if we add "Phone" field from "Available for the Field Set" section to "In the Field Set" section then four fields (Name, Email, Mobile, Phone) will be displayed on visual force without changing the code.