An espresso machine forces water at 90 °C (195 °F) and 9 bar of pressure through a packed cake of finely ground coffee. This process produces a rich, almost syrupy beverage by extracting and emulsifying the oils in the ground coffee.
An espresso machine also has a steam wand which is used to steam and froth milk for milk based espresso beverages such as the cappuccino and latte.
A professional operator of such a machine is now called a barista.