Barcelona's café culture is half Italian and comes with its own set of simple rules: café con leche (cafè amb llet in Catalan) is for breakfast, preferably with a croissant; mid-day, especially after a meal, the locals have an espresso, café solo (un cafè) or a cortado (un tallat), which is an espresso with milk (café Americano is what some would call watered-down versions of the two first coffees); in the afternoon, or after dinner, order a café solo corto, a strong espresso, or a carajillo — a café solo with Spanish brandy.
And since you are in Barcelona, you cannot leave the city without having some crispy churros with a hearty cup of hot chocolate.