The dairy component is essential to the completion of modern coffee creations from tall steamy lattes and frothy cappuccinos, all of which are made from a variety of milk types, ranging from creams down the fat scale to one percent and skim milk, not forgetting soy, rice, lactose free milk (probably for personal or health reasons.)
There are many schools of thought on the type of milk to use for the best frothing results. Some consider using half semi-skimmed and half full fat milk because it tastes 'richer'.
These milk variations have generated a newfound espresso vocabulary that is based on the fat content, quantity and style of milk served in the beverage: "skinny", "tall", "grande", "dry" and so on. Then there are the elusive descriptions of those milks such as frothy, foaming, steaming.
Steamed milk has been heated or scalded to just below the boiling point by the injection of steam or by a heat source. Aeration of the milk is minimal, so the milk's volume is unchanged, and only a small amount of froth.
Frother or foamed millk has been both heated and aerated, by injecting a wand of hot steamat the surface of the milk. This creates a microfoam of tiny air bubbles, giving the milk an ideal consistancy of very light whipped cream.