Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Ethylhexyl Methoxycinnamate is an organic compound that provides UVB protection. It often goes by the more common name of octinoxate. It is created from methoxycinnamic acid and 2-ethylhexanol.

Ethylhexyl Methoxycinnamate absorbs UVB rays with wavelengths between 280-320 nm. UV absorbers protect your skin by using chemical reactions to convert UV rays into heat and energy.

Ethylhexyl Triazone is a modern chemical sunscreen that protects from UV-B radiation.

It is the most effective of existing UV-B filters, as it provides the highest level of photo-stable absorption. It protects from the entire UV-B range (280 to 320nm), with it's highest level of protection at 314nm.

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.

Sodium Hyaluronate is hyaluronic acid's salt form. It is commonly derived from the sodium salt of hyaluronic acid.

Like hyaluronic acid, it is great at holding water and acts as a humectant. This makes it a great skin hydrating ingredient.

Triethanolamine is an emulsifier and pH adjuster. It is created using ethylene oxide and ammonia. This gives Triethanolamine a nitrogen core and a similar scent to ammonia.

As an emulsifier, it prevents ingredients from separating and enhances texture by adding volume to a product.

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.