What is the difference between airs, bubbles, froths and other foams?

Foams are a well known part of modernist cooking, but it has really been around for quite some time. Beer, whipped cream and even the froth on your cappuccino are all foam. As you’ve mentioned, there are different types of foams. Generally, all of these are air that has been trapped within something like water, protein or fat. The differences of foams lie mainly in the characteristics.

Air is a dry and unrefined foam that has a lot of air in it. Dense foam is wet, thicker and finer in texture. In between air and dense foam is light foam. This is lighter than dense foams but finer and wetter than air.

Bubbles are coarse foam that is wetter than airs. These are large and visible, much like bubbles that you can make with soap or shampoo.
Wet and coarse foams are known as froths, this is usually found on top of beverages like lattes and shakes.

Espuma is Spanish term for foam, this type is a hot, dense foam made with a whipping siphon. There are also foams which have a more solid structure known as set foams. These gain their firm composition after being dehydrated or exposed to heat.