A sprocket[1] or sprocket-wheel[2] is a profiled wheel with tooth, or cogs,[3][4] that mesh with a chain, monitor or other perforated or indented materials.[5][6] The name ‘sprocket' applies generally to any wheel upon which radial projections engage a chain moving over it. It is distinguished from a equipment in that sprockets are never meshed together straight, and differs from a pulley in that sprockets have tooth and pulleys are smooth.
Sprockets are found in bicycles, motorcycles, vehicles, tracked automobiles, and other machinery either to transmit rotary movement between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc. Maybe the most common form of sprocket could be found in the bicycle, in which the pedal shaft bears a large sprocket-wheel, which drives a chain, which, subsequently, drives a small sprocket on the axle of the rear wheel. Early automobiles were also largely driven by sprocket and chain system, a practice largely copied from bicycles.
Sprockets are of varied designs, no more than efficiency being claimed for each by the originator. Sprockets typically 
do not have a flange. Some sprockets used with timing belts possess flanges to keep carefully the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to some other where slippage isn't admissible, sprocket chains becoming used rather than belts or ropes and sprocket-wheels rather than pulleys. They could be operate at high speed and some kinds of chain are so constructed concerning be noiseless even at high speed.