Casing is a type of molding that that surrounds the doors of a kitchen or bathroom cabinet. Though its function is primarily decorative, casing can also be used to hide the gap between the jamb of a door and its opening. Casing can also keep doors and windows square to create a more cohesive and appealing design. Casing can be found in a wide variety of styles, such as clamshell, square-edge, colonial and Victorian.