An energy drink is a type of beverage containing stimulant drugs, chiefly caffeine, which is marketed as providing mental or physical stimulation. There are myriad brands and varieties of energy drinks. They generally contain large amounts of caffeine and other stimulants. Many also contain sugar or other sweeteners, herbal extracts and amino acids and may or may not be carbonated. They are a subset of the larger group of energy products, which includes bars and gels.