The purpose of this book is to introduce the readers on the perspective of the role that unsaturated fatty acids and complex lipids play on health and disease. Bioactive lipids can be modified affecting membrane composition, structure and fluidity in addition to changes in cell signaling associated to lipid-protein (membrane receptors) interactions, issues that are addressed by the authors. This book analyzes key topics involving bioactive lipids and their role in normal signaling and the mechanisms of disease. The book navigates from structural studies of oxidized and non-oxidized lipids to the reactions and cell signaling processes that bioactive lipids play in cardiovascular and neurodegenerative diseases. The book contains the recent advances reported in the literature about lipidomics as well as the role that lipid-derived compounds exert on unfolded protein response and lipid metabolism and disease. This book represents a state of the art introduction to lipid metabolism from a biochemical to an in vivo overview being an useful tool for students and investigators. We hope the mechanistic observations on the role of bioactive lipids in health and disease serve a perspective to improve the existing treatments or propose new lipid-based pharmacology.