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 material.[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 should never be meshed together directly, and differs from a pulley for the reason that sprockets have teeth and pulleys are soft.
Sprockets are used in bicycles, chain sprocket motorcycles, vehicles, tracked automobiles, and other machinery either to transmit rotary movement between two shafts where gears are unsuitable or to impart linear movement to a track, tape etc. Probably the most common form of sprocket may be found in the bicycle, in which the pedal shaft bears a sizable sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel. Early automobiles had been 
also largely powered by sprocket and chain mechanism, a practice largely copied from bicycles.
Sprockets are of varied designs, a maximum of efficiency becoming claimed for every 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 in one shaft to some other where slippage isn’t admissible, sprocket chains being used rather than belts or ropes and sprocket-wheels rather than pulleys. They can be operate at high speed plus some kinds of chain are so constructed concerning be noiseless actually at high speed.