This user-friendly and highly readable book presents the basic and intermediate level treatment of modern digital and analog communication systems. The basics of communication systems without using probabilistic concepts are introduced first. With this solid base, the students are ready to master the probabilistic concepts introduced in later chapters. The great strength of the book is in its superb pedagogical style. The book consistenly does an excellent job of explaining difficult concepts clearly, using prose as well as mathematics. Every effort is made to give an intuitive insight-rather than just proofs- as well as heuristic explanations of theoretical results, wherever possible. The clear explanations, the well-chosen examples tp clarify the abstract mathematical results, and excellent illustrations make this text highly informative and easily accessible to an average student. One of the aims in writing this text has been to make learning a pleasant or at least a less intimidating experience for the student by presenting the subject in a clear, understandable, and logically organized manner.