A foaming agent is a material that facilitates the formation of a foam. The term can refer to either 1. a surfactant, which when present in small amounts, reduces the surface tension of the liquid (reduces the work needed to create the foam) and/or increases its colloidal stability by inhibiting the coalescence of bubbles. or 2. A blowing agent, which is the gas or material that forms the gaseous part of the foam.

Sodium laureth sulfate, or sodium lauryl ether sulfate (SLES), is a detergent and surfactant found in many personal care products (soaps, shampoos, toothpastes, etc.). It is an inexpensive and very effective foamer. Sodium lauryl sulfate (also known as sodium dodecyl sulfate or SDS) and ammonium lauryl sulfate (ALS) are commonly used alternatives to SLES in consumer products.

There are two main types of blowing agents, those which are gases at the temperature that the foam is formed and those that generate gases by a chemical reaction. Carbon dioxide, pentane and chlorofluorocarbons are examples of the former. Blowing agents that produce gas via chemical reactions include baking powder, azodicarbonamide, titanium hydride and isocyanates (when they react with water).