This text examines the distinctive physics of plasmas--the form in which most visible matter in the universe is found. The book provides an introduction to plasma particle dynamics, plasma waves, magnetohydrodynamics, plasma kinetic theory, two-fluid theory, and non-linear plasma physics. Rather than emphasizing mathematical considerations, this concise volume concentrates on underlying physical principles. The most advanced background knowledge required consists of Maxwell's equations, and these are reviewed in the introduction. The text will be useful to undergraduates in physics as well as graduates studying astrophysics, nuclear physics, and plasma physics.