What are the three types of moulding?

While architectural millwork includes dozens of specialized profiles, interior moulding is often categorized into three primary functional groups based on where they are installed within a room. The first major category consists of ceiling and upper wall trim, most notably crown moulding, which provides an elegant transition between walls and ceilings while hiding drywall imperfections. The second category comprises floor-level and wall-dividing trim, featuring baseboards that run along the floor to protect walls and chair rails positioned at mid-wall height to prevent furniture damage and support wainscoting panels. The third category encompasses opening and utility trim, which includes door and window casings that frame architectural openings, as well as corner guards and quarter rounds designed to cover expansion gaps and protect high-traffic wall corners throughout residential and commercial interiors.