This compact and well-organized text provides an introduction to plasma physics and shows the interaction of plasmas without any external magnetic fields. It deals with the concepts, processes, and characteristic features associated with plasmas. The interaction of magnetic fields on plasma is purposely excluded in this introductory text to help students grasp the basics first, which makes the understanding of the effects of the magnetic fields easier in the subsequent courses. The book begins with a review of the concepts of kinetic theory of gases, collision phenomena in ionized gases and motion of charged particles. It goes on to give a discussion on the characteristic properties of plasmas and conditions to be satisfied for an ionized gas to show plasma behaviour. In addition, the text covers such topics as transport processes, plasma oscillations, and plasma as a dielectric medium, as a charged fluid, and as a many-body system. Finally, it provides a systematic analysis of important instabilities for an unmagnetized plasma, as well as a discussion on the radiation processes. The organization is systematic and the style lucid, with more physical insight and only relevant mathematics. The text is well illustrated, and the References and Bibliography at the end of the book should stimulate those students who have a desire to study the subject deeper. It is a one-semester text and is designed for the undergraduate, postgraduate and research students of science and engineering who wish to choose plasma physics, astrophysics or space physics as their special areas of study.