Coffee is a drink made from coffee beans, which are the roasted fruit of the Coffea arabica bush. People most commonly drink coffee to relieve mental and physical fatigue and to increase mental alertness. Coffee is also used to prevent Parkinson disease, dementia, and many other conditions, but there is no good scientific evidence to support many of these uses.

Coffee contains caffeine. Caffeine works by stimulating the central nervous system (CNS), heart, and muscles. Coffee also contains other chemicals that might have other benefits. Coffee is darkly colored, bitter, slightly acidic and has a stimulating effect in humans, primarily due to its caffeine content.

Coffee is consumed by about one-third of the world’s population. It is usually served hot, although chilled or iced coffee is common. Sugar, sugar substitutes, milk or cream are often used to lessen the bitter taste or enhance the flavor. It may be served with coffee cake or another sweet dessert, like doughnuts. A commercial establishment that sells prepared coffee beverages is known as a coffee shop.