Tremendous theoretical and experimental developments have recently been made in the sphere of the quantum Hall effect. Among them a field-theoretical approach has presented a fascinating unified physical picture. A most significant feature of the quantum Hall system is that exotic phenomena associated with statistics transmutation are realized. For instance, an electron may undergo Bose condensation by making a charge-flux composite, and fractionally charged excitations (anyons) emerge as quasiparticles. A pedagogical and self-contained discussion on monolayer and bilayer quantum Hall systems is given in a field-theoretical framework, together with an introduction to quantum field theory, anyon physics and Chern-Simons gauge theory. Only knowledge of quantum mechanics is assumed.This invaluable book will be of great interest to students and researchers in condensed-matter, theoretical, particle and mathematical physics.