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 upon which radial projections engage a chain moving over it. It really is distinguished from a equipment in that sprockets should never be meshed together directly, and differs from a pulley in that sprockets have the teeth and pulleys are simple.
Sprockets are used in bicycles, motorcycles, vehicles, tracked automobiles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or even to impart linear movement to a track, tape etc. Maybe the most common form of sprocket may be found in the bicycle, in which the pedal shaft carries a sizable sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the trunk wheel. Early automobiles were also largely driven by sprocket and chain mechanism, a practice generally copied from bicycles.
Sprockets are of various designs, no more than efficiency getting claimed for every by its originator. Sprockets typically don’t have a flange. Some sprockets used with timing belts have flanges to keep carefully the timing belt centered. Sprockets and chains are also utilized for power transmission from one shaft to another where slippage 
is not admissible, sprocket chains being used rather than belts or ropes and sprocket-wheels rather than pulleys. They can be operate at high speed and some kinds of chain are so constructed as to be noiseless also at high speed.