Espresso

Espresso is a concentrated form of coffee produced by forcing hot water under high pressure through finely ground coffee beans. Originating in Italy, espresso has become one of the most popular coffee-brewing methods worldwide. It is characterized by its small serving size, typically 25–30 ml, and its distinctive layers: a dark body topped with a lighter-colored foam called "crema". Espresso machines use pressure to extract a highly concentrated coffee with a complex flavor profile in a short time, usually 25–30 seconds. The result is a beverage with a higher concentration of suspended and dissolved solids than regular drip coffee, giving espresso its characteristic body and intensity. Despite the stronger taste profile, espresso typically contains fewer milligrams of caffeine than a standard serving of drip-brewed coffee.

Source: Wikipedia