The leaves destined to become green tea are processed by withering, rolling and heat treating. Prompt drying ensures the leaves are not oxidized like oolongs or blacks. The leaves also retain a large portion of their vitamins, antioxidants and chlorophyll. Since these teas are unoxidized, the flavor of green tea is much different than oolongs and blacks. It is more vegetative and "herby."
For more information about the health benefits and preparation of green tea, watch this video. Our Chief Leaf explains it all.