This second edition contains much of the content of _Linear Systems and Signals_, Third Edition, by the same authors, with added chapters on analog and digital filters and digital signal processing, plus additional applications to communications and controls. Unlike _Linear Systems and Signals_, Third Edition, in this book the Laplace transform follows Fourier. This book contains enough material on discrete-time systems to be used in a traditional course in Signals and Systems and in an introductory course in Digital Signal Processing.