Uniform treatment of the theory of finite state machines on finite and infinite strings and trees. Many books deal with automata on finite strings, but there are very few expositions that prove the fundamental results of automata on infinite strings and trees. Beginning with coverage of all standard fundamental results regarding finite automata, the book deals in great detail with Büchi and Rabin automata and their applications to various logical theories such as S1S and S2S, and describes game-theoretic models of concurrent operating and communication systems. Self-contained with numerous examples, illustrations, exercises. Suitable for a two-semester undergraduate course for computer science or math majors, or for a one-semester graduate course/seminar. No advanced mathematical background is required, thus the text is also useful for self-study by computer science professionals who wish to understand the foundations of modern formal approaches to software development, validation, and verification.