A sprocket[1] or sprocket-wheel[2] is a profiled wheel with teeth, or cogs,[3][4] that mesh with a chain, track or other perforated or indented material.[5][6] The name ‘sprocket’ applies generally to any wheel where radial projections engage a chain passing over it. It really is distinguished from a equipment in that sprockets should never be meshed together straight, and differs from a pulley in that sprockets have teeth and pulleys are simple.
Sprockets are found in bicycles, motorcycles, vehicles, tracked vehicles, and other machinery either to transmit rotary movement between two shafts where gears are unsuitable or even to impart linear movement to a track, tape etc. Maybe the most typical form of sprocket may be within the bicycle, where the pedal shaft carries a big sprocket-wheel, which drives a chain, which, in turn, drives a little 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 various designs, a maximum of efficiency becoming claimed for each by its originator. Sprockets typically don’t have a flange. Some sprockets used with timing belts possess flanges to keep carefully the timing belt centered. Sprockets and chains are 
also utilized 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 run at high speed and some kinds of chain are so built concerning be noiseless even at high speed.