The understanding of the mechanisms of adipogenesis, the characteristics of lipid metabolism, and the paracrine and endocrine functions of adipose tissue has been improved by new technologies. Adipose tissue is a diverse and complex endocrine organ. Various shades of adipocytes reflect its morphological and functional heterogeneity. Understanding the pathophysiology of obesity and the molecular relationships with type 2 diabetes mellitus, cardiovascular disease, and cancer depends on the study of adipose tissue biology. This book presents information from the existing literature on the origin, characteristics of adipogenesis, and functional properties of adipose tissue as a function of its cellular composition and location.