Bean type:
This refers to the type of coffee plant. Most of the world's production is either Arabica or Robusta.

Bean variety:
The bean varieties differ in taste depending on the growing region, climate, or soil conditions.

Light roasts
Light roasts are characterized by their pleasant acidity and mild aroma. Some coffee connoisseurs even go so far as to detect fruity or floral aromas. These roasts are best suited for filter coffee and not so much for classic espresso from a portafilter.

Medium roasts
Medium roasts are darker than light roasts and have a strong flavor. They are the golden mean, not too strong, not too weak—with a balanced and well-rounded aroma profile. They are also perceived as fuller, which is sometimes explained as coffee with more body.

Dark roasts
Naturally, the darkest roasts are also the strongest. This usually goes hand in hand with a significantly more bitter flavor profile. These roasts have more roasted aromas (but also less coffee aromas and less depth of flavor, because the roasted aromas are more prominent). Southern Italian coffees, for example from Naples, are particularly famous for this. Another advantage is that they have hardly any acidity and no chlorogenic acid, which is harmful to the stomach – and that's good for your health too.

When making your selection, pay attention not only to the roast itself, but also to how the beans were roasted. Industrially produced coffee is roasted in large quantities at high temperatures and in a short period of time. The result is an inferior coffee that is often not completely roasted.

Traditionally drum-roasted coffee, on the other hand, is heated slowly, usually for more than 15 minutes, which also significantly reduces the flavor acidity and chlorogenic acid.

Espresso is prepared in a portafilter machine. This means that the grind size must be specifically adjusted for espresso preparation. An ideal espresso is brewed with high water pressure. The pressure is so high that the flow time is between 25 and 30 seconds. During this time, the water must be able to extract enough substances from the coffee powder to produce a good espresso.

This basically requires a fine grind so that the water can take effect in a short time. If the coffee powder is too coarse, the water cannot work properly and extract the ingredients. The result would be a watery and bland-tasting coffee.