Coffee is a brewed drink prepared from roasted coffee beans, the seeds
of berries from certain Coffea species. When coffee berries turn from
green to bright red in color – indicating ripeness – they are picked,
processed, and dried. Dried coffee seeds (referred to as "beans") are
roasted to varying degrees, depending on the desired flavor. Roasted
beans are ground and then brewed with near-boiling water to produce
the beverage known as coffee. Coffee is darkly colored, bitter,
slightly acidic and has a stimulating effect in humans, primarily due
to its caffeine content. It is one of the most popular drinks in the
world, and can be prepared and presented in a variety of ways (e.g.,
espresso, French press, caffè latte). It is usually served hot,
although iced coffee is common.