Book excerpt: Here is the first volume to examine sulfur in fossil fuels from a geochemical perspective. It begins with six introductory chapters that present an overview of the material, historical background, and summaries of the present state of knowledge. Subsequent chapters cover: case studies of specific sedimentary environments; characterization of sulfur in selected coals and petroleums by various methods and techniques; and the major advances in understanding geochemistry at the molecular level. This important volume fills a significant gap in the technical literature and updates the understanding of the chemical processes in geological environments giving rise to sulfur fossil fuels.