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 gear in that sprockets are never meshed together directly, and differs from a pulley for the reason that sprockets have the teeth and pulleys are easy.
Sprockets are used in bicycles, motorcycles, cars, 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. Perhaps the most typical form of sprocket could be found in the bicycle, in which the pedal shaft bears a sizable sprocket-wheel, which drives a chain, which, subsequently, drives a small sprocket on the axle of the trunk wheel. Early automobiles had been also chain sprocket largely powered by sprocket and chain mechanism, a practice generally copied from bicycles.
Sprockets are of varied designs, no more than efficiency getting claimed for each by the originator. Sprockets typically do not have 
a flange. Some sprockets used in mixture with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission in one shaft to another where slippage is not admissible, sprocket chains getting used instead of belts or ropes and sprocket-wheels instead of pulleys. They can be run at high speed plus some types of chain are so constructed as to be noiseless also at high speed.