How is espresso mainly crafted?

Espresso is mainly crafted by forcing hot water through finely-ground coffee under pressure. This process extracts the rich flavors and oils from the coffee grounds, resulting in a concentrated shot of coffee with a distinctive crema on top. The pressure used during extraction, typically around 9 bars, is crucial as it helps to extract the soluble compounds quickly and efficiently, producing that strong flavor profile that espresso is known for.

Boiling coffee grounds or steeping them, as mentioned in the other options, results in different coffee preparations like drip coffee or French press, which do not achieve the concentrated flavor and body of espresso. Mixing coffee with milk refers to beverages like lattes or cappuccinos, but does not pertain to how espresso itself is crafted. Thus, the correct method of crafting espresso relies specifically on the technique of forcing hot water through the coffee grounds.