The book deals with the propagation and absorption of high frequency waves in plasmas. The text collects in a structured and self-contained way the basic knowledge on the broad and varied behavior of plasma waves, adopting the microscopic kinetic description of the plasma as unifying principle. The internal coherence of the theory is explicitly stressed, and interesting physical phenomena peculiar to plasmas are discussed in detail, including collisionless damping of waves, the development of stochasticity in the interactions of charged particles with electromagnetic waves, and nonlinear interactions between waves. The most common and useful approximations used in solving practical problems are derived as special cases from the more general kinetic approach, thereby clarifying their meaning and domain of applicability. This exposition should be useful to plasma physicists both as an introduction and a reference to this field of research.