A sprocket[1] or sprocket-wheel[2] is a profiled wheel with the teeth, 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 where radial projections engage a chain moving over it. It really is distinguished from a gear in that sprockets should never be meshed together straight, and differs from a pulley in that sprockets have the teeth and pulleys are even.
Sprockets 
are found in bicycles, motorcycles, cars, tracked automobiles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear movement to a monitor, tape etc. Perhaps the most typical form of sprockets 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 little sprocket on the axle of the rear wheel. Early automobiles were also largely powered by sprocket and chain mechanism, a practice mainly copied from bicycles.
Sprockets are of various designs, no more than efficiency getting claimed for each by the originator. Sprockets typically don’t have a flange. Some sprockets used in combination with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to another where slippage is not admissible, sprocket chains becoming used rather than belts or ropes and sprocket-wheels rather than pulleys. They may be run at high speed and some types of chain are so constructed concerning be noiseless even at high speed.