Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of Camellia sinensis, an evergreen shrub native to East Asia which probably originated in the borderlands of south-western China and northern Myanmar.

[9] There are many different types of tea; some have a cooling, slightly bitter, and astringent flavour,[10] while others have profiles that include sweet, nutty, floral, or grassy notes.

[11] An early credible record of tea drinking dates to the third century AD, in a medical text written by Chinese physician Hua Tuo.

[15][16] The more common tea form arrived in the 17th century via the Dutch, who acquired it either indirectly from the Malay teh, or directly from the tê pronunciation in Min Chinese.

[15] The third form chai (meaning "spiced tea") originated from a northern Chinese pronunciation of cha, which travelled overland to Central Asia and Persia where it picked up a Persian ending yi.

The word tú 荼 appears in the Shijing and other ancient texts to signify a kind of "bitter vegetable" (苦菜), and it is possible that it referred to many different plants such as sow thistle, chicory, or smartweed,[23] as well as tea.

[27] The Han dynasty work "The Contract for a Youth", written by Wang Bao in 59 BC,[28] contains the first known reference to boiling tea.

The first record of tea in English came from a letter written by Richard Wickham, who ran an East India Company office in Japan, writing to a merchant in Macao requesting "the best sort of chaw" in 1615.

Peter Mundy, a traveller and merchant who came across tea in Fujian in 1637, wrote, "chaa – only water with a kind of herb boyled in it".

[47] In Britain and Ireland, tea was initially consumed as a luxury item on special occasions, such as religious festivals, wakes, and domestic work gatherings.

[49] Traders from other nations then sought to find another product, in this case opium, to sell to China to earn back the silver they were required to pay for tea and other commodities.

[52] In 1848, Robert Fortune was sent by the East India Company on a mission to China to bring the tea plant back to Great Britain.

[55] Caffeine makes up about 3% of tea's dry weight, which translates to between 30 and 90 milligrams per 250-millilitre (8+1⁄2 US fl oz) cup depending on the type, brand,[56] and brewing method.

[65][66] In clinical research conducted in the early 21st century, it was found there is no scientific evidence to indicate that consuming tea affects any disease or improves health.

[65] Black and green teas contain no essential nutrients in significant amounts, with the exception of the dietary mineral manganese, at 0.5 mg per cup or 26% of the Reference Daily Intake (RDI).

[69] Some varieties can tolerate oceanic climates and are cultivated as far north as Cornwall in England,[70] Perthshire in Scotland,[71] Washington in the United States,[72] and Vancouver Island in Canada.

[69] In addition to a zone 8 climate or warmer, tea plants require at least 127 cm (50 in) of rainfall per year and prefer acidic soils.

The four biggest tea-producing countries are China, India, Kenya and Sri Lanka, together representing 81% of world tea production.

An enzymatic oxidation process triggered by the plant's intracellular enzymes causes the leaves to turn progressively darker as their chlorophyll breaks down and tannins are released.

Without careful moisture and temperature control during manufacture and packaging, growth of undesired molds and bacteria may make tea unfit for consumption.

This can be accomplished through directly adding flavouring agents, such as ginger, cloves, mint leaves, cardamom, bergamot (found in Earl Grey), vanilla, and spearmint.

The order of steps in preparing a cup of tea is a much-debated topic and can vary widely between cultures and individuals.

[95] Historically, the order of steps was taken as an indication of class: only those wealthy enough to afford good-quality porcelain would be confident of its being able to cope with being exposed to boiling water unadulterated with milk.

[96] Higher temperature difference means faster heat transfer, so the earlier milk is added, the slower the drink cools.

Compressed tea is prepared by loosening leaves from the cake using a small knife, and steeping the extracted pieces in water.

During the Tang dynasty, as described by Lu Yu, compressed tea was ground into a powder, combined with hot water, and ladled into bowls, resulting in a "frothy" mixture.

During the Second World War British and Canadian soldiers were issued an instant tea in their composite ration ("compo") packs.

Opposite this large-scale industrial production are many small "gardens," sometimes minuscule plantations, that produce highly sought-after teas prized by gourmets.

[citation needed] India is the world's largest tea-drinking nation,[126] although the per capita consumption of tea remains a modest 750 grams (26 oz) per person every year.

[134] Workers who pick and pack tea on plantations in developing countries can face harsh working conditions and may earn below the living wage.