Sodium cocoyl isethionate (SCI) is a solid surfactant which makes shampoos and soaps foam and cleanse.
Surfactants are organic compounds with a hydrophobic tail and a hydrophilic head. This means they attract oil and water, helping all of the different ingredients in a formula blend together. It also means that they can attract sebum and dirt from the skin and hair and allow them to be washed off with water.
Derived from the fatty acids in coconut oil, SCI is known to be very gentle on the skin and scalp, which is why it is sometimes referred to as "baby foam". This compound is a good sulfate-free alternative for people who want to avoid commonly known surfactants such as sodium lauryl sulfate (SLS).