Written for the one-term course, Essentials of Discrete Mathematics, Third Edition is designed to serve computer science and mathematics majors, as well as students from a wide range of other disciplines. The mathematical material is organized around five types of thinking: logical, relational, recursive, quantitative, and analytical. This presentation results in a coherent outline that steadily builds upon mathematical sophistication. Graphs are introduced early and referred to throughout the text, providing a richer context for examples and applications. Algorithms are presented near the end of the text, after students have acquired the skills and experience needed to analyze them. The final chapter emphasizes the multidisciplinary approach and contains case studies that integrate the fields of biology, sociology, linguistics, economics, and music.