Espresso machine pressure
The brewing pressure used to make espresso, traditionally around 9 bar at the coffee.
Espresso is defined partly by pressure: about 9 bar at the puck is the classic target. Many machines advertise a higher pump pressure (such as 15 or 20 bar), which is the pump's maximum, not what reaches the coffee.
More advertised bars do not mean better espresso; consistent pressure and a good grind matter more.
Why it matters for small spaces
Knowing that a big bar number is marketing helps you avoid choosing a machine on the wrong spec.