Functions of a Complex Variable and Some of Their Applications, Volume I focuses on the fundamental ideas of the theory of functions of a complex variable. This book consists of eight chapters. Chapter I presents the fundamentals of complex analysis, while Chapter II discusses the concept of conformal transformations. The elementary functions are introduced in Chapter III. In Chapter IV, the complex potential for a plane vector field and application of the simplest methods of function theory are elaborated. Chapter V deals with the basic integral theorems, followed by a description of the expansions in series in Chapter VI. Chapters VII and VIII are devoted to the analytical and geometric applications of the theory. This volume is intended for undergraduate and postgraduate students of higher technical institutes and engineers aiming to increase their knowledge of theory.