1. Introduction.- 1.1 General Framework of Exciton Physics.- 1.2 Basic Concepts in Exciton Theory.- 1.3 Appendix: Exciton Self-Trapping.- References.- 2. Internal Structure of Excitons.- 2.1 Overview.- 2.2 Interaction Matrices for Various Mechanisms.- 2.2.1 Electron-Hole Exchange Interaction.- 2.2.2 Cubic Crystals.- 2.2.3 Wurtzite Structure.- 2.2.4 No External Field.- 2.3 Effects of External Perturbations.- 2.3.1 Uniaxial Stress.- Cubic Crystals.- Wurtzite-Type Crystals.- 2.3.2 Electric Field.- 2.3.3 Magnetic Field.- Cubic.- Wurtzite.- 2.4 Supplementary Remarks.- 2.5 Method of Analysis.- References.- 3. Bound Excitons in Semiconductors.- 3.1 Introduction.- 3.2 The Principal No-Phonon States of the Bound Exciton.- 3.2.1 Zero Field Classification of States; the Example of Direct Gap Wurtzite CdS.- General Phenomena.- Classification of Zero Field States.- Oscillator Strength.- Magneto-Optics.- Extension to Other Systems.- 3.2.2 Theory of Exciton Binding.- Effective Mass Theory.- Corrections to Effective Mass Theory from Electron-Phonon Interaction.- Binding at Ionized Donor or Acceptor.- Binding at Neutral Donor or Acceptor.- Electron-Hole Correlation and Exchange.- Bound Exciton Excited States.- Binding at Isoelectronic Impurities.- Isoelectronic Traps in Alloy Semiconductors.- Central Cell Corrections-Haynes Rule.- 3.2.3 The Influence of Site Symmetry on J-J Splittings.- Systems of Lower Symmetry.- Simplified Band Structure and Indirect Semiconductors.- Sublattice Dependences.- Binding at Axial Defects.- Hole-Hole Coupling.- Haynes Rule.- Isoelectronic Donors and Acceptors.- 3.2.4 Magnetic and Uniaxial Stress Perturbations.- Theoretical Framework for Zeeman Effect.- Sources of Magnetic Anisotropy.- Effects of Degeneracy.- Combined Spin Hamiltonians.- Variation with Central-Cell Potential.- Orbital Angular Momentum Excited States.- Quadrati c Zeeman Effect.- Magnetic and Exchange Interactions.- Paschen-Back Effect.- Uniaxial Stress in Zincblende Lattice.- Multivalleló„