A group of organic compounds that cause foaming and serve as cleansing agents based on their surface-active properties. A detergent molecule is termed surface-active because a portion of the molecule is hydrophilic and a portion is hydrophobic. It will therefore collect at the interface of water and another medium such as a gas bubble. Bubbles are stabilized by the surface-active molecules so that when the bubbles rise to the top of the bulk liquid, they maintain their integrity and form a foam. Surface-active agents can also agglomerate by virtue of their hydrophilic/hydrophobic nature to form micelles that can dissolve, trap, and/or envelop soil particles, oil, and grease. Surface-active agents are sometimes called surfactants. Synthetic detergents are sometimes referred to as syndets.