A sprocket, also known as a traction or drive sprocket, is a wheel or cog with teeth designed to transmit motion to a chain, track, or other perforated or recessed material. The term 'sprocket' typically refers to any wheel whose radial teeth engage with a passing chain. Unlike smooth rollers, sprockets have protruding teeth that interact with the chain or track. Unlike gears, sprockets do not mesh directly with each other. They are commonly used in bicycles, motorcycles, cars, tracked vehicles, and various machines to transfer rotational motion between two shafts where gears are not appropriate, or to convert rotational motion into linear movement. While there are several manufacturing methods, the most widely accepted and common is producing them using hobbing machines.