Surface-active agents, also known as surfactants, are one of the common clean agent types. Surfactants work by reducing the surface tension between two substances. For example, in a detergent used for washing clothes, the surfactant in the clean agent type helps to break up the dirt and grease on the fabric. It has a hydrophilic (water-loving) head and a hydrophobic (water-hating) tail. This unique structure allows the surfactant in the clean agent type to surround the dirt particles, with the hydrophobic tails attaching to the dirt and the hydrophilic heads facing the water. As a result, when the fabric is agitated in water, the dirt is lifted away from the surface of the fabric.