Black tea in the context of "Earl Grey tea"

Camellia sinensis is a species of evergreen shrub or small tree in the flowering plant family Theaceae. Its leaves, leaf buds, and stems are used to produce tea. Common names include tea plant, tea shrub, and tea tree (unrelated to Melaleuca alternifolia, the source of tea tree oil, or the genus Leptospermum commonly called tea tree).

White tea, yellow tea, green tea, oolong, dark tea (which includes pu-erh tea) and black tea are all made from two of the five varieties which form the main crops now grown, C. sinensis var. sinensis and C. s. var. assamica, but are processed differently to attain varying levels of oxidation with black tea being the most oxidized and white being the least. Kukicha (twig tea) is also made from C. sinensis, but uses twigs and stems rather than leaves.

Herbal teas or herb teas, technically known as herbal infusions, and less commonly called tisanes, are beverages made from the infusion or decoction of any herbs, spices, or other plant material in water that is not derived from the tea plant (Camellia sinensis). Many herbs used in teas/tisanes are also used in herbal medicine and in folk medicine. Herbal teas are not technically teas because they are not brewed from the tea plant.

The term "herbal tea" is often used to distinguish these infusions from true teas (e.g., black, green, white, yellow, oolong), which are prepared from the tea plant (Camellia sinensis) or, more rarely, its close relatives (such as Camellia taliensis). Beverages actually created from tea and combined with material from other plants are known as "blended teas", "scented teas", or "flavored teas". Examples include jasmine tea, genmaicha, and Earl Grey tea. Unlike true teas, most tisanes do not naturally contain caffeine (though tea can be decaffeinated, i.e., processed to remove caffeine).

Assam tea is a black tea named after Assam, India, the region of its production. It is manufactured specifically from the plant Camellia sinensis var. assamica (Masters). Assam's people tried to plant the Chinese varieties in Assam soil but did not succeed. Assam tea is now mostly grown at or near sea level and is known for its body, briskness, malty flavour, and strong, bright colour. Assam teas, or blends containing Assam tea, are often sold as "breakfast" teas. For instance, Irish breakfast tea, a maltier and stronger breakfast tea, consists of small-sized Assam tea leaves.

The state of Assam is the world's largest tea-growing region by production, lying on either side of the Brahmaputra River, and bordering Bhutan, Bangladesh, Myanmar and very close to China. This part of India experiences high rainfall; during the monsoon period, as much as 250 to 300 mm (10 to 12 in) of rain falls per day. The daytime temperature rises to about 36 °C (96.8 °F), creating greenhouse-like conditions of extreme humidity and heat. This tropical climate contributes to Assam tea's unique malty taste, a feature for which this tea is well known.

White tea may refer to one of several styles of tea which generally feature young or minimally processed leaves of the Camellia sinensis plant.

Currently there is no generally accepted definition of white tea and very little international agreement on how it can be defined. Some sources use the term to refer tea that is merely dried with no additional processing. Therefore, white tea is very close to the natural state of the tea plant. Other sources use the term to refer to tea made from the buds and immature tea leaves picked shortly before the buds have fully opened and traditionally allowed to wither and dry under the sun, while others include tea buds and very young leaves which have been steamed or fired before drying. Most definitions agree, however, that white tea is not rolled or oxidized, resulting in a flavor characterized as lighter than most green or traditional black teas.

Green tea is a type of tea made from the leaves and buds of the Camellia sinensis that have not undergone the withering and oxidation process that creates oolong teas and black teas. Green tea originated in China in the late 1st millennium BC, and since then its production and manufacture has spread to other countries in East Asia.

Several varieties of green tea exist, which differ substantially based on the variety of C. sinensis used, growing conditions, horticultural methods, production processing, and time of harvest. While it may slightly lower blood pressure and improve alertness, current scientific evidence does not support most health benefit claims, and excessive intake of green tea extracts can cause liver damage and other side effects.

Fermented tea (also known as post-fermented tea or dark tea) is a class of tea that has undergone microbial fermentation, from several months to many years. The exposure of the tea leaves to humidity and oxygen during the process also causes endo-oxidation (derived from the tea-leaf enzymes themselves) and exo-oxidation (which is microbially catalysed). The tea leaves and the liquor made from them become darker with oxidation. Thus, the various kinds of fermented teas produced across China are also referred to as dark tea, not be confused with black tea, which is actually referred to as "red tea" (hong cha, 红茶) in Chinese. The most famous fermented tea is pu'er produced in Yunnan province.

The fermentation of tea leaves alters their chemistry, affecting the organoleptic qualities of the tea made from them. Fermentation affects the smell of the tea and typically mellows its taste, reducing astringency and bitterness while improving mouthfeel and aftertaste. The microbes may also produce metabolites with health benefits. Additionally, substances like ethyl carbamate (urethane) may be produced.

Pu'er or pu-erh is a variety of fermented tea traditionally produced in Yunnan Province, China. Pu-erh tea is made from the leaves of the Yunnan tea plant Camellia sinensis var. assamica,which is a specific variety of tea plant that is native to Yunnan Province. It differs from Yunnan tea (Dianhong) in that pu'er tea goes through a complex fermentation process. In the context of traditional Chinese tea production terminology, fermentation refers to microbial fermentation (called 'wet piling'), and is typically applied after the tea leaves have been sufficiently dried and rolled. As the tea undergoes controlled microbial fermentation, it also continues to oxidize, which is also controlled, until the desired flavors are reached. This process produces tea known as hēichá (黑茶), literally "black tea", though the term is commonly translated to English as "dark tea" to distinguish it from the English-language "black tea" (紅茶 hóngchá, lit. "red tea" in Chinese), which it is not.

Most teas, although described as fermented, are actually oxidised by enzymes present in the tea plant. Pu'er is instead fermented microbially by molds, bacteria and yeasts present on the harvested leaves of the tea plant, and thus is truly fermented.