Surfactants are amphiphilic compounds that lower surface tension. They are classified as amphoteric, anionic, cationic, or nonionic. Surfactants work by forming micelles that suspend oils and dirt in water. This allows for cleansing and foaming in cosmetic products. Surfactants also enable emulsification, solubilization, and conditioning. They have various applications including cleansing, foaming, emulsifying oils, creating clear formulas, and improving feel of skin and hair.