Muntins are the thin strips of wood or metal that divide panes of glass in a window or door. They create a grid-like pattern, allowing for multiple smaller panes instead of one large piece of glass. This design can enhance the aesthetic appeal of a building and is often found in traditional architecture. In addition to their decorative function, muntins can also provide structural support for the window. They help to hold the glass in place and can improve energy efficiency by reducing the amount of heat transfer. Muntins are commonly seen in styles like Colonial and Victorian architecture.