A muntin, in architectural and design terminology, refers to a strip of wood or metal that separates and holds panes of glass in a window. Muntins are the vertical or horizontal elements that divide the window into smaller sections, commonly known as lights or lites. Traditionally, muntins were structural elements that helped support the glass, which was produced in smaller panes that were easier to manufacture and transport. In modern times, with the advent of larger sheets of glass, muntins may serve a more decorative purpose, simulating the appearance of multiple panes. They are a distinctive feature in many types of windows, including classic colonial styles, and can vary in width and profile, contributing to the architectural character of a building. Muntins should not be confused with mullions, which are heavier structural elements that can also divide windows but typically separate entire window units within an assembly.