While mega coffee producers use the term “espresso” to refer to coffees that are roasted super dark (think, the remains of a campfire) this is a misuse of the term espresso. Espresso really refers to a method of brewing coffee more than a method of roasting coffee.
The espresso method of brewing coffee can summarized by saying that it is forcing a small amount of hot water through a compressed bed of very finely ground coffee.
This produces about one once of very concentrated coffee. This tiny shot is full of rich coffee flavors, but if you’re not used to drinking straight espresso it can be a little overwhelming. While some people enjoy drinking espresso by itself, most often an espresso is combined with some other ingredient.
Espresso with steamed milk is what makes many of the drinks available at your local coffee shop. Lattes, cappuccinos, macchiatos, and flat whites are all espresso combined with differing amounts and textures of steamed milk. Espresso with hot water makes an americano. Espresso in drip coffee makes a red-eye.
So what is an espresso roast? It is true that any coffee can be used to make espresso, but it is also true that roasters will sometimes roast a coffee slightly darker to help the grounds stand up to the amount of pressure that is produced by the espresso machine.