Rabbeting the edge of shutters is a shaping proceed where one half of the vertical style is removed on each shutter leaf so when closed they meet in a lap-joint. The amount removed through shaping is general equal in depth and height measuring half the thickness of the shutter. Rabbeting is done on opposite edges so when the shutters are open the rabbets are on the outside edges. When the shutters are closed, the lap joint prevents light and air from coming in between the shutter leafs. Also, rabbeting allows additional tolerance when hanging the shutters. A simple rabbet has square edges but a more ornate version involves putting a half-round bead on the face surface of the rabbeted style.