The idea for this book originated with the late Igor Vasil 'evich Kurchatov. He suggested to the author the need for a comprehen sive presentation of the fundamental ideas of plasma physics with out c'omplicated mathematics. This task has not been an easy one. In order to clarify the physical nature of plasma phenomena with out recourse to intricate mathematical expressions it is neces sary to think problems through very carefully. Thus, the book did not come into being by inspiration, but required a considerable ef fort. The aim of the book is to provide a beginning reader with an elementary knowledge of plasma physics. The book is primar ily written for engineers and technicians; however, we have also tried to make it intelligible to the reader whose knowledge ofphys ics is at the advanced-freshman level. To understand the book it is also necessary to have a working knowledge of electricity and magnetism of the kind available in present-: day programs in junior colleges. This book is not intended for light reading. It is designed for the reader for whom plasma physics will be a continuing in terest. We have confidence that such a reader will want to broad en his knowledge by consulting more specialized literature. Thus, we not only include simple expressions but also special important terms."