Sodium Lauroyl Sarcosinate is a cleansing agent and emulsifier. It is a surfactant derived from sarcosine, and a common source is coconut oil.
As a surfactant, Sodium Lauroyl Sarcosinate helps lift dirts, oil, and other molecules to be washed away. In leave-on products, this ingredient is used as an emulsifier. Emulsifier help prevent ingredients such as oils and waters from separating.

Sodium Lauroyl Sarcosinate is also commonly found as a foaming agent in shampoo, toothpaste, and shaving foam. It is amphiphilic, meaning it loves both water and fats.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.