This is the stage during which the hot water comes into contact with the ground coffee, extracting its aromatic substances. In the case of espresso, the water is driven by the pressure produced by the espresso machine within the filter, into which the ground coffee has been placed and tamped. Technically, it is a form of high-pressure percolation (typically 9 bars).

The correct extraction time varies between approximately 25 and 30 seconds.
The factors that influence extraction are grind level, coffee dosage, water temperature and tamping. In the case of an overly fine grind, excessive coffee dosing or too high a temperature, the resulting drink will be
over-extracted, characterised by a slow descent into the cup, dark colour, very persistent crema and a bitter taste.

In the case of an overly coarse grind, insufficient coffee dosing or too low a temperature, the resulting drink will be under-extracted, characterised by a very fast descent into the cup, very light colour, not very persistent crema, acidic taste, little body and a flat aromatic profile with little aftertaste.