The book deals with Physics of a Nanostructure called isolated Quantum Well (QW) in presence of magnetic field applied perpendicular to interfaces of the QW. It contains thorough and complete analytical calculation leading to two transcendental equations satisfied by the magnetic field dependent confined energy levels of isolated GaAs-AlGaAs QWs. The book also contains thorough numerical calculation to bring out effects of the magnetic field on parametric dependence of the confined energy levels. Complete explanations are presented of the results of numerical investigations using a magnetic field dependent effective potential. The book is self-contained; it contains necessary background on Classical Mechanics, Quantum Mechanics, Microelectronics and Nanostructure Physics to enable readers assimilate the book completely.