William Leffler's Petroleum Refining in Nontechnical Language, fourth edition, is designed to give the reader an overview of key refining topics by using relevant analogies, easy-to-understand graphs, formulas, and illustrations. New to this edition is important information on the nature of crude oil and raw materials and a comprehensive discussion on what sets crude oil and oil products price differentials. Also new is a chapter on lubricants as well as the latest technologies employed by refiners. Each chapter was carefully written in nontechnical language to give the reader a basic understanding of the refining industry. The book can be used for self-study, as a classroom textbook, or as a quick reference.