Outer Ego Express Tanning Mousse Versus Cocoa Brown 1 Hour Tan Mousse - Original Medium

Citric Acid is an AHA derived from citrus fruits (think oranges, lemons, and limes!).

As an AHA, Citric Acid removes the top layer of skin cells from the newer layer of skin underneath. This helps skin to remove dark spots and even out skin tone.

Cocamidopropyl Betaine is a fatty acid created by mixing similar compounds in coconut oil and dimethylaminopropylamine, a compound with two amino groups.

This ingredient is a surfactant and cleanser. It helps gather the dirt, pollutants, and other impurities in your skin to be washed away. It also helps thicken a product and make the texture more creamy.

Dihydroxyacetone, or DHA, is a simple sugar. It is frequently used in self-tanning products.

DHA binds to the amino acids in your dead skin cells to create a brown/orange color. Darkening begins to kick in a few hours after application and will continue to develop for up to 3 days. This ingredient can be drying.

Dimethyl Isosorbide is a solvent and helps deliver actives into your skin. It is created from sorbitol.

As a solvent, dimethyl isosorbide helps dissolve other ingredients. This helps ensure even distribution of an ingredient. It may also be used to decrease the thickness of a product.

Ethoxydiglycol is a synthetic solvent.

Solvents are used to keep ingredients together in a product. They can help dissolve ingredients to stable bases or help evenly distribute ingredients throughout the product.

Parfum is a catch-all term for an ingredient or more that is used to give a scent to products.

Also called "fragrance", this ingredient can be a blend of hundreds of chemicals or plant oils. This means every product with "fragrance" or "parfum" in the ingredients list is a different mixture.

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.

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.

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.