An energy drink is a type of drink containing stimulant drugs, usually including caffeine, which is marketed as providing mental and physical stimulation (marketed as "energy", but distinct from food energy). They may or
may not be carbonated and many also contain sugar or other sweeteners, herbal extracts, taurine, and amino acids. They are a subset of the larger group of energy products, which includes bars and gels, and distinct from
sports drinks, which are advertised to enhance sports performance. There are many brands and varieties in this drink category.

Coffee, tea and other naturally caffeinated drinks are usually not considered energy drinks. Other soft drinks such as cola may contain caffeine, but are also not energy drinks. Some alcoholic drinks, such as Buckfast Tonic Wine, contain caffeine and other stimulants. Energy drinks have the effects caffeine and sugar provide, but there is little or no evidence that the wide variety of other ingredients have any effect. Most of the effects of energy drinks on cognitive performance, such as increased attention and reaction speed, are primarily due to the presence of caffeine.