A door closer is a mechanical device that is designed to control the closing of a door. It is commonly used in commercial and residential buildings to ensure that doors close automatically after being opened.

Door closers come in a variety of types and styles, including surface-mounted, concealed, and overhead models. They are typically made of metal or plastic and are powered by springs, hydraulics, or pneumatic systems.

The main function of a door closer is to prevent doors from slamming shut, which can cause damage to the door, frame, and surrounding walls. It also helps to maintain a consistent closing speed, ensuring that the door closes securely and quietly.

In addition to providing safety and convenience, door closers can also help to improve energy efficiency by preventing drafts and reducing heat loss. They are an essential component of any building's access control and safety systems.