Espresso is made by forcing very hot water under high pressure through finely ground, compacted coffee. This process produces an almost syrupy beverage by extracting both solid and dissolved components. It also produces the definitive crema, by emulsifying the oils in the ground coffee into a colloid, which does not occur in other brewing methods. There is no universal standard defining the process of extracting espresso, but there are several published definitions which attempt to place constraints on the amount and type of ground coffee used, the temperature and pressure of the water, and the rate of extraction. Generally, one uses an espresso machine to make espresso. The act of producing a shot of espresso is often termed "pulling" a shot, originating from lever espresso machines, which require pulling down a handle attached to a spring-loaded piston, forcing hot water through the coffee at high pressure. Today, however, it is more common for the pressure to be generated by an electric pump.

Espresso based drinks

In addition to being served alone, espresso is frequently blended, notably with milk (either steamed (without significant foam), wet foamed ("microfoam"), or dry foamed) and with hot water. Notable milk-based espresso drinks, in order of size, include: macchiato, cappuccino, flat white, and latte, while espresso and water drinks especially include the Americano and long black. Others include the red eye and latte macchiato. The cortado, piccolo, and galão are made primarily with steamed milk with little or no foam.

In order of size, these may be organized as follows:

  • Traditional macchiato: 35–40 ml, one shot (30 ml) with a small amount of milk (mostly steamed, with slight foam so there is a visible mark)

  • Modern macchiato: 60 ml or 120 ml, one or two shots (30 or 60 ml), with 1:1 milk

  • Cortado: 60 ml, one shot with 1:1 milk, little foam

  • Piccolo: 90 ml, one shot (30 ml) with 1:2 milk, little foam

  • Galão: 120 ml, one shot with 1:3 milk, little foam

  • Flat white: 150 ml, one or two shots (30 or 60 ml), with 1:4 or 2:3 milk

  • Cappuccino: 150–180 ml, one or two shots (30 or 60 ml), with wet foam to create a dome shape.

  • Latte: 240–600 ml, two or more shots (60 ml), with 1:3–1:9 milk