This book explains the calculations of Laughlin and Schrieffer and shows how they are modified when the magnetic length is treated properly. The attachment of flux quanta to the electron has been discussed at length and experimental reports are re-examined in the light of variable magnetic length. The angular momentum theory of the Quantum Hall Effect explains the experimental data as is well based on theoretical grounds. An effort is made to compromise the flux-attached electron theory with the angular momentum theory which shows that some of the composite fermions become bosons. The Quantum Hall effect is explained on the basis of angular momentum theory. The importance of the negative spin has been discussed. The considerable amount of literature is reviewed.