An A to Z Guide to Understanding Skin Care

We spell it out for you

When it comes to shopping for new beauty products, we usually go only by packaging. We look for key words or phrases like “clears acne” or “for fine lines and wrinkles”--not the scientific gibberish that fills the back label (and all those ads you see everywhere). But sometimes it’s best to be educated on what exactly is going on your face. Here, an alphabetical guide to some of the most commonly used skin-care terms and ingredients.

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Antioxidants: You hear this term thrown around everywhere. But really, what the hell does it mean? Well, antioxidants are substances that stop damaging oxidizing agents and free radicals (more on that later) from prematurely aging skin. They can be found in grapes, blueberries, fish and dark leafy greens.

Beta hydroxy acid: An organic compound similar to alpha hydroxy acids (that you've also surely heard of), this popular skin-care ingredient is used in exfoliants and peels to treat acne, pigmentation and fine lines.

Collagen: This is the protein found in connective tissue that keeps skin firm and tout. As we age, we lose our natural collagen but can beef it up with amino-acid-rich foods like rice and beans.

Differin: A popular brand of prescription acne and keratosis treatment, this topical gel is high in vitamin A.

Emollient: An ingredient vocab lesson for ya: This is any ingredient that increases water levels in the epidermis (the top layer of skin); also known as moisturizer.

Free radicals: OK, now for the topic du jour. These are molecules in your skin with an odd number of electrons (caused by oxidation) that accumulate as you age (and hyper-accumulate with pollution and sun exposure), causing damage to your skin. Hence, the need for antioxidants. 

Glycolic acid: Here we have an alpha hydroxy acid derived from sugarcane that dissolves the glue-like substance that binds skin cells together. It is used to exfoliate skin and improve its texture.

Hyaluronic acid: A sugar molecule that is found naturally in the skin, its primary function is to increase moisture content and prevent water loss. It is typically found in creams and serums.

Idebenone: Popular in anti-aging products, this potent antioxidant helps to protect against environmental damage by fighting off free radicals.

Jojoba oil: The most similar to the skin’s own sebum, this lightweight oil absorbs quickly and hydrates without clogging pores.

Kaolin: This claylike mineral is a regular ingredient in cleansers and face masks because of its ability to absorb oil and remove dead skin cells.

Lycopene: Commonly found in tomatoes and carrots, this antioxidant helps protect skin from sun damage (and is pretty great for your heart and veins, too).

Mexoryl SX: Another fun science lesson: This popular stabilizing ingredient is used in sunscreen to protect skin from UVA rays (the ones that cause premature aging).

Niacinamide: A form of vitamin B3, this compound strengthens the skin's outer layers, improves elasticity and soothes any redness or irritation. And you can find it wherever vitamins are sold.

Oxybenzone: Now, back to sunscreen. This ingredient absorbs UVB rays, so it is often combined with avobenzone (which absorbs UVA light) to create broad-spectrum sun protection.

Peptides: These are tiny protein particles that signal your skin to produce collagen (which, again, helps to plump up fine lines and wrinkles). You'll often see them marketed as ingredients in moisturizers and anti-aging creams.

Quercetin: If you see this on any of your product labels, know that it's an antioxidant derived from purple grapes and green tea to fight free-radical damage.

Retinol: Long considered the gold standard in anti-aging ingredients, this vitamin A derivative encourages cell turnover and increases the production of hyaluronic acid and collagen--which makes it a great treatment for acne, reducing hyperpigmentation and smoothing fine lines.

Salicylic acid: Commonly found in products for acne-prone skin, this beta hydroxy acid removes excess oil and dead cells from the skin's surface to help keep it clear.

Titanium dioxide: Sounds fancy but it's just a mineral filter found in many all-natural sunscreen formulas that shields the skin from UVA and UVB rays.

Urea: A potent humectant (read: any ingredient that attracts water from the environment to the skin), it is often used in moisturizers because of its ability to keep skin moist while also exfoliating dead skin cells.


Vitamin C: Yeah, yeah, you know what vitamin C is. But did you know it goes beyond fighting just colds? Also known as ascorbic acid, this antioxidant boosts collagen production and inhibits pigment formation to treat and prevent spots from forming.

Whey protein: Derived from milk, this supplement (popular in powdered form for protein shakes) is actually known to strengthen skin, hair and nails, in addition to the obvious muscular benefits.

Xanthan gum: This natural thickening agent helps to stabilize liquids in skincare products--and pretty much everything else in our lives.

Yeast extract: When applied topically, this reparative ingredient improves the firmness and smoothness of skin without being too abrasive.

Zinc oxide: A commonly used ingredient in sunscreen, this gentle filter offers UV protection with an extremely low risk of irritation, making it ideal for sensitive skin types.

Jenny Jin Headshot Vertical 2023

Beauty Director

Jenny Jin is PureWow’s Beauty Director and is currently based in Los Angeles. Since beginning her journalism career at Real Simple magazine, she has become a human encyclopedia of...