Every beauty term, explained. ✦

The slightly acidic film (pH 4.5–5.5) on the skin surface formed by sebum, sweat, and amino acids. First line of defence against bacteria and environmental aggressors.

The resurfacing acid that reveals fresh, glowing skin underneath.

The active growth phase of the hair follicle cycle. Lash anagen phase lasts 30–45 days; scalp hair lasts 2–7 years.

Molecules that neutralise free radicals before they damage skin cells, DNA, and collagen. Key antioxidants: Vitamin C, Vitamin E, Niacinamide, Green Tea, Resveratrol.

The gentle powerhouse for hyperpigmentation and hormonal acne — safe for pregnancy.

The skin's ability to retain moisture and keep irritants out. Maintained by the stratum corneum's ceramide-rich lipid matrix.

The pore-clearing acid that gets inside blackheads and dissolves them.

Prostaglandin analog (Latisse brand) — the only FDA-approved prescription medication for eyelash growth. Results: 25% length increase, 106% fullness at 16 weeks.

The ancient healing plant that calms inflammation and strengthens skin overnight.

The mortar that holds your skin barrier together — your skin's greatest healer.

Using acids (AHAs, BHAs, PHAs) to dissolve the bonds between dead skin cells without physical scrubbing.

The primary structural protein of the skin, providing firmness and elasticity. Produced by fibroblasts. Declines at ~1% per year after age 30.

Refers to ingredients or products that can block pores and contribute to comedone (blackhead/whitehead) formation. Rated 0–5; 0 = non-comedogenic.

The middle layer of the skin containing collagen, elastin, fibroblasts, blood vessels, and hair follicles. Where most skin treatments aim to have their effect.

Androgen hormone converted from testosterone by 5-alpha-reductase enzyme. Primary driver of androgenic alopecia (hair thinning). Finasteride blocks its production.

Two-step cleansing: first an oil-based cleanser (removes oil-based makeup and SPF), then a water-based cleanser (removes remaining residue). Gold standard for PM cleansing.

Protein in the dermis that allows skin to spring back after being stretched. Works alongside collagen. Difficult to restore once lost — prevention is key.

The outer layer of the skin. Contains the stratum corneum, keratinocytes, and melanocytes. Continuously renews itself every 28–40 days.

Removal of dead skin cells from the surface. Can be physical (scrubs, tools) or chemical (acids, enzymes). Goal: reveal fresher skin and improve product absorption.

Cells in the dermis responsible for producing collagen, elastin, and hyaluronic acid. Stimulated by retinol, microneedling, laser, and peptides.

Unstable molecules generated by UV, pollution, and metabolism that damage DNA, collagen, and skin cells. Neutralised by antioxidants.

The resurfacing acid that reveals fresh, glowing skin underneath.

Ingredient that attracts and binds water to the skin. Key humectants: hyaluronic acid, glycerin, panthenol, aloe vera. Must be paired with an occlusive to lock moisture in.

The hydration molecule — holds 1,000× its weight in water.

Excess melanin production causing dark spots. Types: post-inflammatory (from acne/injury), melasma (hormonal), and solar (from UV damage).

Mineral pigments used in makeup to create skin tones. Unique benefit: provide visible light (VL) protection — critical for melasma and hyperpigmentation management.

The predominant cell type in the epidermis. Produce keratin and migrate from the basal layer to the stratum corneum over 28–40 days.

The gentler AHA — exfoliates and hydrates simultaneously.

Essential omega-6 fatty acid that forms part of the skin barrier. Deficiency linked to comedone formation. Found in rosehip oil, hemp seed oil, sea buckthorn.

Network of vessels that carries fluid, waste, and immune cells from tissues to lymph nodes. Stimulated by facial massage, gua sha, and MLD for puffiness reduction.

The pigment produced by melanocytes that gives skin its colour. Produced in response to UV exposure. Excess production causes hyperpigmentation.

Pigment-producing cells in the basal layer of the epidermis. Produce melanin in response to UV and inflammatory signals.

Hormonal hyperpigmentation appearing as symmetrical patches on the face. Triggered by UV, hormones (pregnancy, OCP), and heat. One of the most difficult pigmentation conditions to treat.

The phenomenon where two objects look the same colour under one light source but different under another. Why foundation that matched in-store looks different in daylight.

Cleansing water containing micelles — tiny surfactant spheres with water-loving outer shells and oil-loving cores that capture makeup and debris.

The ecosystem of bacteria, fungi, and microorganisms living on the skin surface. A balanced microbiome protects against pathogens and supports barrier function.

Enzymes that break down collagen and other extracellular matrix proteins. Activated by UV exposure. Antioxidants and retinol help reduce their activity.

The gentle multi-tasker — minimises pores, calms redness, fades spots.

A product or ingredient that has been tested and found not to block pores or cause comedone formation. Not a regulated term — look for ingredients with comedogenicity ratings of 0–1.

Ingredients that create a physical barrier on the skin surface to reduce water loss. Examples: petrolatum, lanolin, beeswax, dimethicone, shea butter. Must be applied as the last step of skincare.

Chemical reaction with oxygen that degrades products and can darken foundation shades. Foundation oxidation is when a formula appears darker after 30–60 minutes of wear.

The symbol on cosmetic packaging indicating how many months a product is safe to use after opening. 6M = 6 months, 12M = 12 months, 24M = 24 months.

Tiny collagen messengers that tell your skin to produce more of itself.

Skin's ideal pH is 4.5–5.5 (slightly acidic). Disrupting this with alkaline products (pH 7+) damages the acid mantle and weakens the barrier.

Dark spots that develop after skin inflammation — from acne, eczema, or injury. More pronounced in darker skin tones. Takes 3–12 months to fade.

Lipid compounds that act as local hormones. Prostaglandin analogs (like bimatoprost) extend the anagen phase of hair follicles, causing significant lash and brow growth.

The glow ingredient that resurfaces your skin overnight.

Chronic inflammatory skin condition causing persistent central facial redness, visible vessels, and flushing. Four subtypes with different treatment approaches.

Oily substance produced by sebaceous (oil) glands in the skin. Provides natural barrier protection but excess production leads to oily skin and comedones.

The lightweight oil your skin already makes — pure hydration without clogging pores.

The outermost layer of the epidermis — 15–20 layers of dead corneocytes in a ceramide-rich lipid matrix. The primary barrier function of the skin.

The passive loss of water through the skin to the environment. Elevated TEWL = compromised barrier. Measured by tewameter. Reduced by ceramides and occlusives.

The targeted dark spot eraser — gentler and safer than hydroquinone.

Prescription-strength retinoic acid (the active form of vitamin A). The most potent topical retinoid — requires prescription. More effective than OTC retinol but also more irritating.

The enzyme responsible for melanin production. Targeted by brightening ingredients — niacinamide, alpha-arbutin, kojic acid, and azelaic acid all inhibit tyrosinase activity.

The underlying warm, cool, or neutral tone in skin that remains constant regardless of surface tan. Warm undertones appear golden/yellow; cool are pink/blue; neutral is a mix.

UVA (aging) and UVB (burning) radiation from the sun. UVA penetrates glass and clouds; UVB causes sunburn. Both contribute to skin aging, pigmentation, and cancer.

Your skin's morning shield — brightens, protects and builds collagen.

The most important anti-aging ingredient you will ever use.