This book has a pedigree. It has developed from earlier publications by the author and from his experience over 50 years in reading, writing, thinking, and working with lipids and fatty acids. The earlier publications are: (i) An Introduction to the Chemistry of Fats and Fatty Acids, Chapman and Hall, 1958. (ii) An Introduction to the Chemistry and Biochemistry of Fatty Acids and their Glycerides, Chapman and Hall, 1967. (iii) Lipids in Foods: Chemistry, Biochemistry, and Technology (with F. A. Norris), Pergamon Press, 1983. (iv) The Lipid Handbook (with J. L. Harwood and F. B. Padley), Chapman and Hall, first edition 1986, second edition 1994. (v) A Lipid Glossary (with B. G. Herslof), The Oily Press, Dundee, 1992. (vi) Lecture notes for a course on Fatty Acids and Lipids designed for those entering the oil and fat industry and given on over 20 occasions since 1977. The book is dedicated to the next generation of lipid scientists. The study of lipids now involves many disciplines, all of which require a basic knowledge of the chemical nature and properties of these molecules, which is what this book is about. It is written particularly for those who, with some knowledge of chemistry or biochemistry, need to know more about the nature of lipids and fatty acids.