This book focuses on the applications that motivate the development and use of combinatorics. The application examples covered include defective products, disease screening, genome mapping, satellite communication, web data, search engines, telecommunications traffic, smallpox vaccinations, sound systems, oil drilling, dynamic labor markets, and distributed computing. This edition includes new material on list colorings, the inversion distance between permutations and mutations in evolutionary biology, graph coloring, relations, DNA sequence alignment, cryptography, automorphisms of graphs, orthogonal arrays, secret sharing, the RSA cryptosystem, consensus decoding, and Menger's theorems.