Moka pots, also known as stove top espresso makers, are similar to espresso machines in that they brew under pressure and the resulting brew shares some similarities, but in other respects differ. As such, their characterization as "espresso" machines is at times contentious, but due to their use of pressure and steam for brewing, comparable to all espresso prior to the 1948 Gaggia, they are accepted within broader uses of the term, but distinguished from standard modern espresso machines.
Moka pots are similar to espresso machines in that they brew under pressure, produce coffee with an extraction ratio similar to that of a conventional espresso machine, and, depending on bean variety and grind selection, moka pots can create the same foam emulsion known as crema that conventional espresso machines can.
Moka pots differ from espresso machines in that they brew under substantially lower pressure – 1.5 bars (21 psi) rather than 9 bars (130 psi) – and use hotter water – a mix of boiling water and steam at above 100 °C (212 °F), rather than 92–96 °C (198–205 °F) of espresso machines, similar to early steam brewing machines.
The bottom chamber contains the water. The middle chamber is a filter-basket holding the ground coffee and sits within the bottom chamber. The top chamber, with a metal filter, screws onto the bottom chamber. When the pot is heated on a stove, the pressure from the steam in the bottom chamber forces the water through a tube into the filter-basket, through the ground coffee, the metal filter, and it then funnels into the top chamber where the coffee is then ready to serve. They are commonly found in Italy, Spain and Portugal. They are also known as a macchinetta, Italian for little machine or caffettiera, Italian for coffee maker.