A ratchet is a mechanical device that allows motion in one direction while preventing it in the opposite direction. It typically consists of a gear with teeth and a pawl that engages with the teeth, enabling the gear to turn only in one direction. This mechanism is commonly used in tools like socket wrenches and bicycle freewheels. Ratchets are essential in various applications, providing safety and efficiency. For example, in lifting equipment, ratchets help secure loads, preventing accidental release. Their design ensures that once a load is lifted or a task is completed, it remains in place until intentionally released.