For courses in undergraduate Combinatorics. Many new detailed applications are covered, including material on list colourings, expanding discussion of scheduling legislative committees, material on DNA sequence alignment, and material on cryptography. *NEW Section dealing with stable marriages and their many modern applications, including the assignment of interns to hospitals, dynamic labour markets, and strategic behaviour. *A mix of difficulty in topics with careful annotation that makes it possible to use this book in a variety of courses. *Treatment of applications as major topics of their own rather than as isolated examples. *Use of real applications from the current literature and the extensive modern literature citations. *Problem-solving through a variety of exercises that test routine ideas, introduce new concepts and applications, or attempt to challenge the reader to use the combinatorial techniques developed.