Microfoam is finely textured milk used for making espresso-based coffee drinks, particularly those with latte art. It is typically made with the steam wand of an espresso machine, which pumps steam into a pitcher of milk.
The opposite of microfoam is macrofoam (also called dry foam, in contrast to the wet foam of microfoam), which has visibly large bubbles, a style of milk traditionally used for cappuccinos.