A seat belt is a safety device designed to secure passengers in motor vehicles, reducing their risk of injury or being ejected from the vehicle during an accident. It typically consists of a lap and shoulder strap that fastens across the body, connecting to a metal buckle on either side. The purpose of wearing a seat belt is to minimize the impact of sudden stops or collisions by keeping passengers in their seats, reducing the likelihood of injury from contact with interior components of the vehicle or being ejected through an open window or door.