Hinges attach doors to structures or surfaces and allow them to open and close. They are used in new construction and retrofit projects. Door and butt hinges are available in screw-in and weld-on styles. Concealed hinges are invisible when the door is closed to help provide a neat appearance. Lift-off hinges allow the door to be removed from the door frame without having to uninstall the hinges first, making them suitable for high-traffic areas and businesses that receive frequent deliveries. Spring hinges are used in residential, hospitality, and healthcare facilities to keep doors closed when they're not in use.