A driven gear is a gear that is turned by another gear, known as the driving gear. In a gear system, the driving gear transfers its motion to the driven gear, causing it to rotate. This interaction is essential in various machines, such as bicycles, watches, and automobiles, where precise movement is required. Driven gears can vary in size and shape, affecting the speed and torque of the output. Larger driven gears typically rotate more slowly but provide greater torque, while smaller ones rotate faster but with less torque. Understanding this relationship is crucial in designing efficient mechanical systems.