Sometimes referred to as Montmorillonite, this absorbent clay is derived, most often, from weathered volcanic ash. Rich in antibacterial minerals, it’s commonly used in “purifying” or “detoxifying” cleansers and masks, as it pulls pollutants, sebum, and grime from pores.

An acne medicine that kills pimple-causing bacteria and exfoliates pores. It can be found in concentrations up to 10 percent in over-the-counter products.

These chemical exfoliants can smooth fine lines, even pigmentation, and penetrate deeply into pores, dissolving sticky plugs of sebum and dead skin. One of the most common BHAs, salicylic acid, is found in many acne washes, creams, and peels.

Small amounts of the B Vitamin that are found in carrots, almonds, milk, and other foods. Aside from helping the body process fats and sugars, oral biotin is important for regulating hair and nail growth. reduces hair breakage and increases elasticity.

A skin blemish that forms when the sebum (oil) draining from a pore becomes blocked by a clump of dead skin cells. Its color results from the sebum's pigment, which darkens when exposed to air.

A plant compound that nourishes skin and is a common ingredient in under-eye creams and gels because of its anti-inflammatory effects; it decreases puffiness and constricts blood vessels to reduce dark circles.

A broad term referring to the way cells send information using proteins and other signaling molecules — and receive information from inside or outside the body via receptor sites located on cell membranes. Increasing numbers of skin creams contain ingredients, like retinol, carnosine, and peptides, claiming to bind to receptor sites and encourage cells to behave like younger, healthier versions of themselves.

Found in many fruits, the antioxidant alpha hydroxy acid acts as a natural preservative. When used in peels, masks, and washes, it brightens and exfoliates the upper layers of the skin, encouraging new collagen formation.

A broad term for a pore, or hair follicle, that's blocked by sticky dead skin cells and the sebum that can't drain properly. When the follicle remains open, the sebum's pigment darkens from air exposure, forming a blackhead. When P. Acnes bacteria invade the clogged pore, the resulting inflammation creates a whitehead.

This severe form of acne that develops when a plug of dead skin cells, sebum, and P. Acnes bacteria lodges deep inside a pore, creating a tender, pus-filled bump that sometimes ruptures the pore wall, spreading to surrounding tissue.

A natural carbohydrate, DHA is the active ingredient in most sunless tanners.

The most common form of a chronic noncontagious skin disorder which is  atopic dermatitis.

Eczema is characterized by itchy, red, scaly patches that often show up on the inner elbows, behind the knees, and around the neck and eyes. 

Stretchy structural proteins that allow skin to snap back into place, elastin is particularly vulnerable to sun damage.

Any ingredient that increases water levels in the epidermis. Synonym: moisturizer.

Plentiful in connective tissue throughout the body, including the dermis, these cells produce the collagen and elastin responsible for keeping skin pliant and springy. Topical retinoids ramp up collagen production in fibroblasts.

Highly unstable molecules created in the body by sunlight, cigarette smoke, and pollution that latch onto and damage cells in ways that can lead to roughness, sagging, and wrinkling.

Typically sourced from papaya, pineapple, and pumpkin, they break down the keratin proteins comprising dead skin cells, offering a mild form of exfoliation.

Boasting antioxidant levels that are far more powerful than vitamins E and C, topical and oral formulations of the ingredient are used to protect the skin against UV damage and other environmental assaults.

Pressed from the seeds of industrial hemp plants, this supercharged moisturizer packs vitamins, minerals, and inflammation-quelling essential fatty acids.

The trademarked name for a four-step exfoliating treatment consisting of a gentle acid peel, vacuum pore extraction, a moisturizing cocktail of hyaluronic acid and antioxidants.

Often triggered by UV light exposure, a wound, illness, hormonal changes, or certain drugs, this darkening of the skin may look like patches of discoloration or an isolated acne scar.

Similar in structure to skin's natural oil, it penetrates skin to hydrate without clogging pores.

A skin condition whereas red bumps on the legs and back of arms occur. This takes place when sticky cells within the hair follicle clump together to form a plug, preventing them from being whisked away through routine exfoliation. This common condition, believed to be genetic, can be minimized but not cured with lactic acid creams or scrubs.

Light-emitting diode devices give off a narrow range of a specific wavelength of light. (Different wavelengths target different skin issues; for example, blue light kills the bacteria known to cause acne.) Much less intense than lasers or IPL, many LED devices are safe enough for hand-held use at home.

A mix of purified water, hydrators (like glycerin), and low doses of mild surfactants, these no-rinse liquid cleansers attract makeup, oil, and dirt when swiped over skin with a cotton pad. They're mild enough for sensitive and acne-prone complexions.

Abundant in herring, mackerel, wild salmon, walnuts, flaxseed, and olive oil, these essential fatty acids maintain the function of cell membranes throughout the body, preserving cells' ability to take in nutrients, dispose of waste, and hold onto water. In the epidermis, this can translate to smoother, more supple, hydrated skin.

A family of chemicals that work as preservatives, this group of ingredients includes methylparaben, propylparaben, butylparaben, and ethylparaben. Parabens can be irritating to some complexions, per the EWG. But the larger concern is that parabens may disrupt some hormones in the body. The FDA notes that there is currently no information that proves that parabens in skin-care products and cosmetics are hazardous to your health, but they add that studies are ongoing.

A measure of the acidity or alkalinity of a substance. Water has a neutral pH of 7. A healthy skin barrier has an acidic pH of 4.5 to 5.5. And pH-balanced skin-care products generally fall on the slightly acidic side of neutral.

An antioxidant found in grapes, it neutralizes free radicals to protect skin cells from damage.

A chronic skin disease marked by persistent redness, easy flushing, broken blood vessels, and pimples on the nose and cheeks primarily. Rosacea tends to run in families, especially those of Northern or Eastern European descent. The cause is unknown; there is no cure; and controlling triggers (heat, UV, spicy foods, alcohol) is crucial to treatment.

A skin-care product that contains high concentrations of active ingredients and claims superior penetration of the skin's surface when app

A skin-care product that contains high concentrations of active ingredients and claims superior penetration of the skin's surface when applied.

A key ingredient in chemical peels used to treat sun damage and hyperpigmentation, TCA promotes shedding of the outermost layer of dead skin cells, allowing new cells to rise to the surface in the days following treatment. TCA peels are generally light to medium strength, with the former requiring a series of two to three for best results; the latter requiring only a single session (but carrying about a week of downtime).

An antioxidant that boosts collagen production and inhibits pigment formation. Like many antioxidants, it's an unstable molecule that can break down quickly when exposed to light and air. Common derivatives, like ascorbyl palmitate and tetrahexyldecyl ascorbate, tend to be more stable than pure ascorbic acid but slower acting.

This moisturizing antioxidant protects against free-radical damage.