Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially available. There are also various coffee substitutes. Typically served hot, coffee has the highest sales in the world market for hot drinks. Coffee can be prepared and presented in a variety of ways (e.g., espresso, French press, caffè latte, or already-brewed canned coffee). Sugar, sugar substitutes, milk, and cream are often added to mask the bitter taste or enhance the flavor.

Source: Wikipedia