The primary ingredient in foam soap is surfactant, which creates the foaming action that is characteristic of this type of soap. Surfactants reduce the surface tension of the liquid, allowing it to spread and create a rich lather when dispensed. Common surfactants used in foam soaps include sodium lauryl sulfate or sodium laureth sulfate. Additionally, foam soaps often contain water, moisturizers, fragrances, and preservatives to enhance the user experience and ensure product stability. The formulation provides effective cleaning properties while being gentle on the skin, making foam soap popular for both personal and commercial use.