Tea is a beverage which is obtained through infusing the dried leaves of the Camellia sinensis plant. Depending on the leaves' level of oxidation, the four basic types of tea include: white tea, green tea, oolong tea and black tea. The chemical composition of tea varies depending on crop, on climate and on tea processing method. Among tea's components, we could mention theine, which is an alkaloid similar to the one found in coffee, maté, cola nuts, tannin and essential oils. The tea-plant originates in South-Eastern Asia, in the region formed by North-Eastern India, in the north of Burma (Myanmar) and by Yunnan province (China). Tea has been first used by the Chinese in the province of Yunnan, both for foods and for beverages. Because tea was extremely important for the Asian cultures, there have been many legends regarding its discovery. One popular tea legend says that Emperor Shen Nung has discovered tea while he was drinking hot water from a bowl in the shadow of a tree, in the year 2737 BC. A few leaves fell into the Emperor's bowl, changing the water's color. As he was curious by nature, Shen Nung took a sip and was surprised by the beverage's flavor and refreshing properties. In India, there is another tea-related legend saying that Prince Dharma, touched by divine grace, went to China in order to spread Buddha's teachings. As he wanted to make himself worthy of such holy mission, he took a vow never to sleep during the nine years of his spiritual journey. By the end of the third year, however, he began to feel drowsy, unable to keep his eyes open. By pure chance, he plucked some leaves and began chewing them. Surprisingly, he found his strength again and he continued his preaching for another six years. The Japanese version of the same legend is slightly different. After three years of his mission the same Bodhi Dharma fell asleep while praying, as he was obviously exhausted. When he woke up, he felt angry for his bodily weakness and cut off his eyelids and threw them to the ground, and a few years later, when he returned to the same spot, he saw some bush had grown in the very same place where he had thrown his eyelids. He tasted the leaves and thus noticed that they had the quality of keeping somebody awake. He told others about the quality of those leaves, and tea became popular in that region. Putting these legends aside, the tea bush apparently came from China. The approximate region is somewhere around the border between Yunnan province and North Vietnam. The drinking of tea was initially developed by the Chinese people. Around the years 648-749, tea was introduced in Japan by a Buddhist monk named Gyoki. He planted tea bushes in 49 temple gardens. Much later, in the 13th century, a Zen priest created the Tea Ceremony (Cha-no-yu). The popularity of tea drinking increased during the Chinese Tang Dynasty (618-907 AD), evolving into one of the most favorite pastimes. It thus moved from the pharmacology field and became a re-find part of day-to-day life. When tea-houses appeared, tea became a source of artistic inspiration for people such as poets, potters, painters. Artists actually created a sort of sophisticated world around tea, charged with symbolism. Lu Yu (723-804 AD), wrote the first tea treatise, Cha Jing or "Traditions of Tea", a work describing the nature of the tea-plant and which standardized beverage's methods of preparing and drinking. He said that "One finds in the serving of tea the same harmony and order that govern all things." During that time, tea was made with the help of compressed plants which were initially roasted and then ground into powder, and after that they were mixed with boiling water. After that, some ingredients were added, such as rancid butter, salt and spices. Tea is still taken in this style in present-day Tibet. Tea was also planted in some other Asian countries which have turned into worldwide producers, such as ex-British African colonies, in Argentina or Reunion Island. Tea is the second most drunk beverage in the world after water. About 15,000 cups are drunk every second.