Leafy vegetables contain carbohydrates, proteins, fatty acids, and minerals. Additionally, they possess a high content of fiber and vitamins. Therefore, Leafy vegetables are considered the most important component of a balanced human diet. Leafy vegetables are also a source of specialized metabolites, including phenolics, flavonoids, terpenoids, alkaloids, and glucocinolates, which have very high nutraceutical values. Consequently, leafy vegetables are considered nutritious and healthy food to overcome various diseases such as diabetes, cancer, obesity, metabolic syndrome, cardiovascular diseases, as well as improve risk factors related to these diseases. This book discusses the nutritional value, bioactive components, and biological activity of green leafy vegetables from around the world.