The importance of foam in a liquid and the requirements for it vary considerably depending on the application. Foam is a desirable feature in shower gels and shampoos, in detergents, in shaving creams, or in beverages such as beer; whereas in industrial processes, it often causes problems and must therefore be avoided. For this reason, the properties of foam—from its formation to its breakdown—are defined and tested during the product development phase. Foam is a dispersion of a gas in a liquid or solid. The volume of the gas is relatively greater than that of the other phase. Foams in liquids are usually stabilized by amphiphilic substances, such as surfactants, particulates, or other compounds. Spherical foam or wet foam forms when there is a large amount of dispersing agent or liquid between the gas bubbles. The liquid causes the gas bubbles to take on a spherical shape (the smallest surface area for the largest volume). In polyhedral foam or dry foam, the distance between individual gas bubbles decreases, and the dispersing agent contracts into lamellae. Spherical foam and polyhedral foam often occur simultaneously, with the polyhedral foam situated above the spherical foam. Gravity causes the liquid to flow downward from the foam lamellae. There are many methods for characterizing and analyzing foam, and they generally follow an application-oriented approach. For example, in the evaluation of dishwashing detergents, the dish test is widely used, in which dirty dishes are washed until the foam layer of the detergent liquid disappears. In this and other manual tests, foam is generated by agitating, stirring, or pouring by hand, and the stability and quantity of the foam are evaluated visually. The reliability of these tests depends largely on the training and experience of the personnel. Instrumental methods mimic manual tests but ensure reproducible processes and quantitative evaluations that are independent of the operator thanks to technological implementation. Foam-generation methods are also based on mechanical principles such as agitation, shaking, beating, pouring, spraying, or air injection. SITA’s FoamTester generates foam through agitation using a mechanical disc. Two optical, non-contact measurement systems provide the data needed to characterize foam properties, such as volume, stability, liquid drainage, and foam structure (morphology).