The spectrum of eating disorders varies widely, ranging from mildly abnormal eating habits to life-threatening chronic disease. Given the many different cultural food norms and individual preferences, along with the fact that dieting behavior is extremely common, it can be challenging to differentiate unusual eating behaviors from clinically significant eating disorders. In this article, the authors provide an introduction to eating disorders including anorexia nervosa, bulimia nervosa, and eating disorders not otherwise specified, focusing on the clinical presentation, epidemiology, and prognosis.