Creates custom write panels to manage post custom fields.
Fields is a WordPress plugin that let you manage write panels in your write/edit page. Fields supports post types that can have UIs.
With Fields, you can define boxes which appear in your write panels. A box can contain a number of groups which are sets of custom fields that you can define. Boxes are displayed as meta boxes and groups are shown as tabs that can be switched inside boxes. Within a group, fields can be shown as either textfields, textarea, drop boxes, radio group or check boxes.
Fields does not create custom post types, to do so, use other plugins such as WP Post Type UI.
Brief structure of Fields: