A door closer is a mechanical device that automatically closes a door after it has been opened. It helps ensure that doors shut securely, which can improve safety and energy efficiency by preventing drafts. Door closers are commonly used in commercial buildings, schools, and hospitals, where frequent door use is expected. These devices work by using a hydraulic or pneumatic mechanism to control the speed and force of the door as it closes. This prevents slamming and reduces wear on the door and its frame. Properly installed door closers can enhance accessibility and convenience in various environments.