Machines that “require physical force to press the water through the bed” of coffee are classified as manual, Welch says. The difference between manual and automatic espresso machines also comes down to technique. These amounts vary slightly depending on equipment and the barista’s preference.
According to a Smithsonian article about the history of espresso machines, Italian coffee chain Illy specifies water should be between 190 to 200 degrees Fahrenheit and under 9 atmospheres of pressure or more. Water temperature and pressure are critical. The process involves pulling water through the cake, or bed, of packed ground coffee to extract a shot of coffee into your glass. Essentially, espresso is concentrated coffee “generally prepared quickly under pressure,” Welch says. An espresso refers to how you prepare a drink rather than the type of coffee bean you use or its roast.
