Black teas such as Assam, Ceylon, Keemun, Earl Grey, and Darjeeling come mainly from India, Sri Lanka, Africa, and China. Black tea is fully oxidized and brews a dark amber colour. It is higher in caffeine, approximately 50 mg per 180-ml (6-oz) cup. Brew 3-7 minutes.
White tea contains withered and dried leaves with slight oxidation. The result is a mild and sweet tea with low caffeine (15-20 mg) and light colour. One of the nicest white teas is Silver Needle. Brew with 75-80 C (165-175 F) water. Brew 1-3 minutes.
Green teas like Jasmine, Sencha, Gyokuro, Mao Feng, Gunpowder and Genmaicha are not oxidized and brew to a pale green or gold colour. Most originate in Japan or China. Green teas are mild and delicate and can have a light grassy or vegetal flavour, or even, in the case of Gunpowder, a smoky taste. Be careful to use boiled water that has cooled for a minute or two, to 75-80 C (165-175 F), otherwise the leaves will be burned and cause the tea to have a bitter taste. Caffeine content is low, about 20-30 mg per cup. Brew 1-3 minutes.
Matcha is a type of finely-ground green tea, usually from Japan. It is made not by steeping and removing the tea, but by whisking the powder into hot water and drinking the brew as is. Use not-quite-boiling water as for green tea.
Oolong is a partially oxidized tea and lies somewhere between green and black. It can be re-steeped several times. Caffeine content is between 30-40 mg. Steeping temperature is 90-100 C (195-210 F). Brew 1-3 minutes