Linear Systems and Signals, Third Edition, is a textbook for the required junior-year signals and systems course in the typical Electrical Engineering department curriculum. The book's success lies in its thorough, inclusive presentation of key concepts supported by a unique, bottom-up explanation of the theories and reasoning behind the material. The heuristic approach is a trademark of Dr. Lathi's books and a vital reason why instructors who adopt the text stick with it. This text shares many topics and features with Dr. Lathi's Signal Processing and Linear System, but differs in its sequence of topics, particularly in the placement of the Laplace transform ahead of the Fourier Transform. The two books cover much the same ground but their different organizations mirror the two different approaches in wide use by instructors.