Tea is made from the tea plant Camellia sinensis. There are four major categories of tea: white, green, oolong and black. The categories refer to how much a tea is oxidized. Oxidation is the natural process that changes the color and flavor of the tea leaf as it is exposed to air. Green tea is slightly oxidized and thus it retains its natural appearance and vibrant color. Green tea varies dramatically in flavor from grassy and sweet, to floral and fresh, to nutty and roasted. Green tea's flavor depends on the plant varietal, season of harvest, soil, elevation, weather, cultivation and origin. Darjeeling tea is grown in the Darjeeling district in West Bengal, India.