Coffee is a widely-consumed stimulant beverage prepared from roasted seeds, commonly called coffee beans, of the coffee plant. Coffee was first consumed in the 9th century, when it was discovered in the highlands of Ethiopia.[1] From there, it spread to Egypt and Yemen, and by the 15th century had reached Armenia, Persia, Turkey, and northern Africa. From the Muslim world, coffee spread to Italy, then to the rest of Europe, Indonesia and the Americas. Today, coffee is one of the most popular beverages worldwide

Coffee berries, which contain the coffee bean, are produced by several species of small evergreen bush of the genus Coffea. The two most commonly grown species are Coffea canephora (also known as Coffea robusta) and Coffea arabica. These are cultivated in Latin America, Southeast Asia, and Africa. Once ripe, coffee berries are picked, processed, and dried. The seeds are then roasted, undergoing several physical and chemical changes. They are roasted to varying degrees, depending on the desired flavor. They are then ground and brewed to create coffee. Coffee can be prepared and presented in a variety of ways.

Coffee has played an important role in many societies throughout modern history. In Africa and Yemen, it was used in religious ceremonies. As a result, the Ethiopian Church banned its consumption until the reign of Emperor Menelik II of Ethiopia. It was banned in Ottoman Turkey in the 17th century for political reasons, and was associated with rebellious political activities in Europe.

Coffee is an important export commodity. In 2004, coffee was the top agricultural export for 12 countries, and in 2005, it was the world’s seventh largest legal agricultural export by value.

Some controversy is associated with coffee cultivation and its impact on the environment. Many studies have examined the relationship between coffee consumption and certain medical conditions; whether the effects of coffee are positive or negative is still disputed.

Coffee is usually propagated by seeds. The traditional method of planting coffee is to put 20 seeds in each hole at the beginning of the rainy season; half are eliminated naturally. Coffee is often intercropped with food crops, such as corn, beans, or rice, during the first few years of cultivation.

Map showing areas of coffee cultivation
r:Coffea canephora
m:Coffea canephora and Coffea arabica.
a:Coffea arabica.

The two main cultivated species of the coffee plant are Coffea canephora and Coffea arabica. Arabica coffee (from C. arabica) is considered more suitable for drinking than robusta coffee (from C. canephora); robusta tends to be bitter and have less flavor than arabica. For this reason, about three-quarters of coffee cultivated worldwide is C. arabica. However, C. canephora is less susceptible to disease than C. arabica and can be cultivated in environments where C. arabica will not thrive. Robusta coffee also contains about 40–50 percent more caffeine than arabica. For this reason, it is used as an inexpensive substitute for arabica in many commercial coffee blends. Good quality robustas are used in some espresso blends to provide a better foam head and to lower the ingredient cost. Other cultivated species include Coffea liberica and Coffea esliaca, believed to be indigenous to Liberia and southern Sudan, respectively.

Most arabica coffee beans originate from either Latin America, eastern Africa, Arabia, or Asia. Robusta coffee beans are grown in western and central Africa, throughout southeast Asia, and to some extent in Brazil. Beans from different countries or regions usually have distinctive characteristics such as flavor, aroma, body, and acidity. These taste characteristics are dependent not only on the coffee’s growing region, but also on genetic subspecies (varietals) and processing. Varietals are generally known by the region in which they are grown, such as Colombian, Java, or Kona.

From: Wikipedia,http://en.wikipedia.org/wiki/Coffee