Coffee is a widely consumed beverage prepared from the roasted seeds commonly referred to as beans of the coffee plant. Though sometimes served cold, it is typically served hot. A typical 7 fluid ounce cup of coffee contains 80-140 milligrams of caffeine, depending on the bean and method of roasting and preparation. Some people drink coffee "black" (plain), others sweeten their coffee or add milk, cream or non-dairy creamer. The majority of all caffeine consumed worldwide comes from coffee, as much as 85% in some countries. Coffee, along with tea and water, is one of the most popular beverages world-wide, its volume amounting to about a third of that of tap water in North America and Europe. In 2003, coffee was the world's sixth largest agricultural export in value, behind wheat, maize, soybeans, palm oil and sugar.

Etymology:
The English word "coffee" is believed to be derived ultimately from the Arabic word qahhwa; it is called bunn or bunna in Ethiopia in Amharic and bunni in Tigrinya, and other variations on the original bunn in other languages. Coffee's Arabic name, qahwa, is a truncation of qahwat al-bunn, or wine of the bean. Traditional Islam prohibited the use of alcohol as a beverage, and coffee proved to be a suitable alternative.

The Arabic qahhwa was borrowed by Ottoman Turkish as kahve, which in turn was borrowed into Italian as caffè with French, Portuguese and Spanish as café. Early forms date back to the last decade of the 16th century, but the word "coffee" itself did not come into use until the early to mid 1600s.

History of coffee:
The history of coffee can be traced to at least as early as the 9th century, when it appeared in the highlands of Ethiopia, from which it spread to Egypt and Yemen, and by the fifteenth century had reached Persia, Turkey, and northern Africa.

From the Muslim world, coffee spread to Europe, and became popular there during the seventeenth century. The Dutch were the first to import it large-scale into Europe, and eventually smuggled in some seedlings in 1690, defying the Arab prohibition on exporting the plants or unroasted seeds. The Dutch later grew the crop in their colony of Java. In 1538, Leonhard Rauwolf, a German physician, after returning from a ten-year trip to the Near East, gave this description of coffee: "A beverage as black as ink, useful against numerous illnesses, particularly those of the stomach. Its consumers take it in the morning, quite frankly, in a porcelain cup that is passed around and from which each one drinks a cupful. It is composed of water and the fruit from a bush called bunnu."

When coffee reached the American colonies, it was initially not as successful as it had been in Europe, as colonists found it a poor substitute for alcohol. However, during the Revolutionary War, the demand for coffee increased so much that dealers had to hoard their scarce supplies and raise prices dramatically; this was partly owing to the reduced availability of tea from British merchants. After the War of 1812, in which Britain had temporarily cut off access to tea imports, the Americans' taste for coffee grew during the early nineteenth century, and high demand during the American Civil War together with the advancements of brewing technology secured the position of coffee as an everyday commodity in the United States. Today coffee is a common beverage of the North American breakfast and morning commute.

The Plant:
There are two main species of the coffee plant, the older one being Coffea arabica. Coffee is thought to be indigenous to south-western Ethiopia, specifically from Kaffa, from which it may have acquired its name. While more susceptible to disease, it is considered by most to taste better than the second species, Coffea canephora (robusta). Robusta, which contains about 40-50% more caffeine, can be cultivated in environments where arabica will not thrive and probably originated in Uganda. For this reason it is used as an inexpensive substitute for arabica in many commercial coffee blends. Compared to arabica, robusta tends to be bitter and has little flavor, with a telltale "burnt rubber" or "wet cardboard" aroma and flavor. Good quality robustas are used in some espresso blends to provide a better "crema" (foamy head), and to lower the ingredient cost. In Italy, many espresso blends are based on dark-roasted robusta. The large industrial roasters use a steam treatment process to remove undesirable flavors from robusta beans for use in mass-marketed coffee blends.[13] Other species include Coffea liberica and Coffea esliaca, believed to be indigenous to Liberia and southern Sudan respectively.

Arabica coffees were traditionally named by the port from which they were exported, the two oldest being Mocha, from Yemen, and Java, from Indonesia. The modern coffee trade is much more specific about origin, labeling coffees by country, region, and sometimes even the producing estate. Varietal is a botanical term denoting a taxonomic category ranking below species, a designation more specific than arabica or robusta and unrelated to the coffee's place of origin. Coffees consisting entirely of beans from a single varietal, bourbon, for example, are generally so referred to, with a reference to their place of origin (as in: Rwanda Blue Bourbon). Coffee aficionados may even distinguish auctioned coffees by lot number.

Most arabica coffee beans originate from one of three growing regions; Latin America, East Africa/Arabia and Asia/Pacific. Beans from different countries or regions usually have distinctive characteristics such as flavour (flavour criteria include terms such as "citrus-like" or "earthy"), aroma (sometimes "berry-like" or "flowery"), body or mouthfeel, and acidity. Acidity refers to a tangy or clean-tasting quality, typically present in washed or wet processed coffees. It does not refer to a coffee's pH level. (Black coffee has a pH of around 5). These distinguishing taste characteristics are dependent not only on the coffee's growing region, but also on its method of process and genetic subspecies or varietal.

A peaberry, (also sometimes called a "Caracoli" bean) is a coffee bean that develops singly inside the coffee cherry instead of the usual pair of beans. This situation occurs 5-10% of the time. Since flavour is concentrated when only a single bean is grown inside the cherry, these beans (especially Arabica) are highly prized.