Micelles are microscopic, spherical aggregates of surfactant molecules. Each surfactant molecule has a hydrophilic (water-loving) head that is attracted to water molecules and a hydrophobic (water-hating) tail that repels water and simultaneously attaches itself to the oil and grease in dirt. These opposing forces loosen dirt and suspend it in the water which is wiped away on the cotton pad. Micellar cleansers are used without water and are especially suitable for sensitive skin.