This is a book about the science behind whisky: its production, its measurement, and its flavor. The main purpose of this book is to review the current state of whisky science in the open literature. The focus is principally on chemistry, which describes molecular structures and their interactions, and chemical engineering which is concerned with realizing chemical processes on an industrial scale. Biochemistry, the branch of chemistry concerned with living things, helps to understand the role of grains, yeast, bacteria, and oak. Thermodynamics, common to chemistry and chemical engineering, describes the energetics of transformation and the state that substances assume when in equilibrium. This book contains a taste of flavor chemistry and of sensory science, which connect the chemistry of a food or beverage to the flavor and pleasure experienced by a consumer. There is also a dusting of history, a social science.