Delicate oolong teas are known as semi-fermented teas. During production, freshly plucked leaves are exposed to oxygen until they have reached the mid-way point between green and black teas before drying. Oolong teas are most closely associated with growers in China and Taiwan. Historically, they were enjoyed in tiny cups and sipped slowly to promote meditative thinking. Like green teas, these are best served as-is with no milk or sweetener. Oolong teas are known to be medium-high in antioxidants, and usually have similar caffeine levels as green teas or slightly lower.