Kinetic theory is defined as a branch of statistical mechanics that attempts to describethe non-equilibrium properties of macroscopic systems in terms of microscopic propertiesof the constituent particles or quantum excitations. The history of kinetic theory is summarizedfrom the first understandings of the connections of temperature and pressure ofperfect gases with their average kinetic energy and with the average momentum transferto the walls by particle-wall collisions. The history continues with a discussion of the contributionsof Maxwell and Boltzmann, and the development of the Boltzmann transportequation. Modern developments include extending the Boltzmann equation to moderatelydense gases, formulation of kinetic theory for hard sphere systems, discovery of long timetail contributions to the Green-Kubo expressions for transport coefficients, applications ofkinetic theory to fluctuations in gases, to quantum gases and to granular particles. Thecontents of each chapter are then summarized.