Gears are mechanical devices that transmit motion and force between different parts of a machine. They consist of toothed wheels that interlock, allowing one gear to turn another. This interaction can change the speed, direction, and torque of the movement, making gears essential in various applications, from simple toys to complex machinery. Gears come in various shapes and sizes, including spur gears, bevel gears, and worm gears. Each type serves a specific purpose, such as changing the angle of rotation or increasing torque. Gears are commonly found in everyday items like bicycles, clocks, and automobiles, playing a crucial role in their functionality.