There are two main species of the coffee plant, Coffea arabica being the older one. Coffee is thought to be indigenous to south-western Ethiopia, specifically from Kefa, from which it may have gotten 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. This has led to its use 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. Other species include Coffea liberica and Coffea esliaca, believed to be indigenous to Liberia and southern Sudan respectively.

Brazil remains the largest coffee exporting nation, but in recent years the green coffee market has been flooded by large quantities of robusta beans from Vietnam.Many experts believe the giant influx of cheap green coffee after the collapse of the International Coffee Agreement of 1975-1989 with Cold War pressures led to the prolonged pricing crisis from 2001 to 2004.In 1997 the "c" price of coffee in New York broke US$3.00/lb, but by late 2001 it had fallen to US$0.43/lb. Robusta coffees (traded in London at much lower prices than New York's Arabica) are preferred by large industrial clients (multinational roasters, instant coffee producers, etc.) because of their lower cost.

The preference of the "Big Four" coffee companies for cheap robusta is believed by many to have been a major contributing factor to the crash in coffee prices, and the demand for high-quality arabica beans is only slowly recovering. After the crash, many coffee farmers in Africa, Indonesia and South and Central America lost their livelihoods, or turned to illicit crops such as coca to earn a living. The Dutch brand 'Max Havelaar' started the concept of fair trade Labelling, which attempted to remedy the situation by guaranteeing coffee growers a negotiated pre-harvest price; many smaller roasters and recently Proctor & Gamble and Starbucks have joined Fair Trade. Another issue with coffee is ecological: the American Birding Association has led a campaign for sustain ably harvested, shade-grown and organic coffees vs. the newer mono-cropped full-sun varieties, which lead to deforestation and loss of bird habitat.

Coffee has its history as far back as the 9th century. It is thought to have originated in the highlands of Ethiopia and spread to the rest of the world via Egypt and Europe. The word coffee is derived from the Arabic word Qah'wa over Ottoman Turkish Kahve, which originally meant wine or other intoxicating liquors. Partly due to the Islamic prohibition on drinking wine, preparing and drinking coffee became an important social ritual. The effects of coffee were such that it became forbidden among orthodox and conservative imams in Mecca at 1511 and at Cairo in 1532 by a theological court. In Egypt, coffeehouses and warehouses containing coffee berries were sacked. But the product's popularity, particularly among intellectuals, led to the reversal of this decision in 1524 by an order of the Ottoman Turkish Sultan Selim I. In the 15th century, Muslims introduced coffee in Persia, Egypt, northern Africa and Turkey, where the first cafeteria, Kiva Han, opened in 1475 in Constantinople.

From the Muslim world, coffee spread to Europe, where it became popular in the 17th century. Dutch traders were the first to start large scale import of coffee into Europe. In 1538, Léonard Rauwolf, a German physician, having come back from a ten-year trip in the Near East, was the first westerner to describe the brew: "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." These remarks were noted by merchants, who were sensitive to this kind of information through experience in the commerce of spices. English coffeehouses were centers of intellectual and commercial activity. Lloyds of London, the famous insurance firm, was originally a coffeehouse.

Many studies have been performed on the relationship between coffee consumption and many medical conditions, ranging from diabetes and cardiovascular disease to cancer and cirrhosis. Studies are contradictory as to whether coffee has any specific health benefits, and results are similarly conflicting with respect to negative effects of coffee consumption. In addition, it is often unclear whether these risks or benefits are linked to caffeine or whether they are to be attributed to other chemical substances found in coffee (and whether decaffeinated coffee carries the same benefits or risks).

One fairly consistent finding has been the reduction of diabetes mellitus type 2 in coffee consumers, an association that cannot be explained by the caffeine content alone and indeed may be stronger in decaffeinated coffee.

Recently, coffee was found to reduce the chances of developing cirrhosis of the liver: the consumption of 1 cup a day was found to reduce the chances by 20%, and 4 cups a day reduced the chances by 80%.

A commonly held belief about coffee is that drinking it at a young age will "stunt your growth".

Agriculture