This classic graduate-level volume was the first general but simple introduction to the fields of plasma and fusion research. Since its original publication in 1956, it has served as a valuable reference. Designed for those who have had an introductory course in theoretical physics but are otherwise unacquainted with the detailed kinetic theory of gases, it chiefly emphasizes macroscopic equations and their consequences. The contents are restricted to topics offering a theoretical understanding of plasma and fusion research. Subjects include the motion of a particle, macroscopic behavior of a plasma, waves in a plasma, equilibria and their stability, and encounters between changed particles. A helpful appendix offers background on the Boltzmann equation. Author Lyman Spitzer, Jr., was the first to propose the idea of placing a large telescope in space, and he was the driving force behind the development of the Hubble Space Telescope. Founder and director of Princeton's Plasma Physics Laboratory, a pioneering program in controlled thermonuclear research, Spitzer taught and inspired a generation of plasma physicists.