A universal joint, often referred to as a U-joint, is a mechanical device that allows for the transmission of rotary motion between two shafts that are not in a straight line. It consists of two yokes connected by a cross-shaped component, enabling flexibility in movement. This design helps accommodate misalignment and changes in angle between the shafts. Universal joints are commonly used in various applications, including automobiles, industrial machinery, and aerospace systems. They play a crucial role in transferring power from the engine to the wheels in vehicles, allowing for smooth operation even when the drive shafts are at different angles.