Foam is an object formed by capturing pockets of gas in a fluid or solid. A bathroom sponge as well as the head on a glass of beer are instances of foams. In a lot of foams, the volume of gas is large, with thin films of fluid or strong separating the areas of gas.
Solid foams can be closed-cell or open-cell. In closed-cell foam, the gas kinds discrete pockets, each completely bordered by the solid material. In open-cell foam, gas pockets connect to every various other. A bath sponge is an instance of an open-cell foam: water easily streams via the whole framework, displacing the air. An outdoor camping floor covering is an example of a closed-cell foam: gas pockets are secured from each other so the mat can not absorb water.
Foams are instances of spread media. In basic, gas is existing, so it separates right into gas bubbles of different dimensions (i.e., the material is polydisperse) — divided by fluid areas that might develop films, thinner and also thinner when the fluid phase drains pipes out of the system films.  When the principal scale is tiny, i.e., for an extremely fine foam, this spread tool can be considered a type of colloid.
Foam can additionally describe something that is analogous to foam, such as quantum foam, polyurethane foam (foam rubber), XPS foam, polystyrene, phenolic, or several various other manufactured foams.