Surfactants cleanse and build foam by acting at the surface between fat and water (surface-active agents or surfactants). They are able of being mixed with water and fat of the skin, allowing dirt to be removed. Based on their cleansing power surfactants are classified into primary and secondary or co-surfactants. Based on the chemical structure there are anionic, amphoteric, non-ionic, and quaternary agents. Surfactants form the base of all personal cleansing products and can also have wetting, conditioning, defatting, emulsifying, & thickening effects.

Surfactants are also very useful for homemade soaps (particularly liquid soaps) to improve lathering and decrease harshness. They are added to the oil-lye mixture during the boiling procedure. Surfactants greatly accelerate and improve the soap making process.

SLS (sodium lauryl sulphate). It has this reputation as an extremely drying terrible ingredient. However, there is a reason why it is used in shampoo.

Imagine washing your hair with just plain water.

From a chemical view point, scrubbing your hair and using warm water will help dislodge some oil, but really not that much

Washing your hair with SLS containing shampoo

When a surfactant such as SLS is used, oil can be dissolved away from the hair. The hair is left squeaky clean and oil free. This is because SLS can form micelles which help carry the oil away during the rinsing of the shampoo.

Now not everyone wants squeaky clean hair. Curly hair does pretty well with some oil on it. However if you are trying to get rid of a silicone product, have too much oil on your hair or have used a product that you didn't like and your conditioner isn't helping you, some SLS shampoo may actually work to give you a clean slate.