Yes, green tea does contain caffeine. An 8-ounce cup of green tea typically contains between 25 to 50 milligrams of caffeine, which is less caffeine than black tea and considerably less than coffee. The exact amount can vary depending on factors such as the type of green tea, how it is grown, processed, and brewed. For example, bagged green teas tend to have more caffeine than loose leaf teas, and powdered green teas like matcha have more caffeine than both bagged and loose green teas. Green tea contains a natural stimulant caffeine, but also contains L-theanine, an amino acid that works synergistically with caffeine to provide a gentler and steadier stimulation, which can help with focus and relaxation without the jittery effects commonly associated with other caffeinated drinks. In summary: yes, green tea has caffeine, but in lower amounts than many other common caffeinated beverages, providing a milder and calming boost.