Making outstanding coffee is pure alchemy - as much art as science is involved. There are countless variables: the barista, her technique, the machine, the grinder, the humidity, the air temperature, the grind-setting. The temperature and pressure of the water. The beans, of course - how recently they've been roasted, the wash method, their country of origin and how they're blended together to meet milk.
But so much of that is invisible to you, the consumer. You see your friendly inked and bearded barista and need to know: can I trust the coffee he's making?