Propylene Glycol is an odorless, colorless liquid. As a humectant, it helps skin retain moisture. It also aids in delivering active ingredients.

Another role of this ingredient is preventing a product from melting or freezing. Propylene glycol also adds antimicrobrial properties to a product, elongating product lifespan.

Propylparaben is a preservative and is a paraben with antifungal and antimicrobial properties.

This ingredient can be naturally found in plants and insects, but most of it is synthetically manufactured for human use. In cosmetics, it is usually created by reacting para-aminobenzoic acid and propanol (an alcohol).

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.