Cholesterol is a class of organic molecules called lipids. It helps hydrate your skin and is essential to having a healthy skin barrier.

Our skin naturally contains cholesterol in the outermost layer. Besides cholesterol, it also contains ceramides and fatty acids. Cholesterol makes up about 1/4 of your skin's outer layer and barrier. Your skin barrier is responsible for keeping allergens and microbes out. Having a healthy skin barrier is also responsible for keeping your skin firm and plump.

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

A study from 2016 found glycerin to be more effective as a humectant than AHAs and hyaluronic acid.

Hydrogenated Lecithin is created from the hydrogenation of lecithin (a group of phospholipids). Hydrogenation is a chemical reaction between hydrogen and another element.

This ingredient is an emollient and emulsifier. As an emollient, it helps soften skin by trapping moisture within. As an emulsifier, it prevents oil and water ingredients from separating.

Phenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.

It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.

Saccharide Isomerate comes from sugars found in corn. It is a skin hydrator.

The structure of this ingredient can be altered to be more similar to the carbohydrates found in our skin. This ability to mimic our skin gives it hydrating properties.

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.