It consists of passing water through finely ground coffee.
Making a real espresso requires a professional espresso machine and barista’s professional knowledge, i.e. following the so-called 4M rule.
The 4M rule The
final quality of an espresso depends on four factors:
Miscela – Coffee blends
Macina Caffe – Grinder
Machina – Coffee maker machines
Mano – A manual activity performed by the bartender