Trim consists of all the material used in your home to conceal edges, finish joints, or add decoration to a room. This includes, baseboards, window and door casings, and ceiling moldings. Since the edges of trim have to fit together closely, careful measurement and cutting are essential when installing trim. Use a utility knife to mark your cut lines, since pencils tend to dull quickly and won't draw as precise a line as you need. Use a miter (*MITE-er) box to make your cut on the outside of this line, since the saw will remove some of the wood, leaving you with a piece of trim that's too short. To repair dents in existing trim, drive a finishing nail into the depression and leave the head sticking out slightly. This will help hold the wood filler in place when you fill the hole. When it's completely dry, sand it smooth and repaint the area. Nail holes in trim are usually filled with painter's putty, rather than spackle. Just rub it over the hole, and it fills it quickly. This technique can't be used on nail holes in walls, since painter's putty tends to bleed through flat latex finishes.