Espresso machine

An espresso machine is a device that brews coffee by rapidly forcing heated, pressurized water through a small, compressed cake (commonly called a puck) of finely ground coffee and a coffee filter to produce a thick, concentrated coffee called espresso.

Espresso machines vary significantly in design and operation. They may be steam-driven, piston-driven, pump-driven or air-pump-driven, and may be manual, semi-automatic, or fully automatic in operation. An espresso machine may even incorporate a built-in coffee grinder, and, in the case of a superautomatic machine, mechanisms for automating the entire process, such that a shot of espresso may be produced by a single touch from the user. They range in size and application from small appliances to much larger commercial appliances and coffee vending machines, including 'prosumer' machines which combine commercial or professional features in consumer machines.

Despite this variety, many espresso machines may be understood to share some common elements, such as a portafilter (comprising a filter basket, a locking mechanism, and an attachment method such as a handle) and a grouphead to which it attaches prior to the brewing process, and through which the heated, pressurized water is introduced to the puck of ground coffee prior to filtration.

An espresso machine may also have an auxiliary steam wand (or wands) used to steam and froth milk or non-dairy milks for coffee drinks such as cappuccino and caffè latte, including microfoam which may be used for latte art. Some machines can automate this milk heating and texturing process to some degree; some (like the Cerēs Robo Coffee) may even be capable of acting as autonomous baristas.