Skincare Glossary

The plain-English glossary — comedogenic, the skin barrier, TEWL, pH, the Fitzpatrick scale and every term that trips people up. Quick, accurate definitions you can trust.

Core Glossary

Comedogenic: What It Means & How to Read Labels

Comedogenic means an ingredient or product is likely to clog pores and trigger blackheads.

Fitzpatrick Skin Types: What They Are & Why They Matter

Fitzpatrick skin types (I–VI) classify how skin responds to UV light.

Humectant vs. Emollient vs. Occlusive: The Moisturizer Map

Humectants draw water into skin, emollients smooth and soften it.

Skin Cycling: The 4-Night Routine, Explained by Evidence

Skin cycling is a 4-night rotation: exfoliant, retinoid, then two recovery nights.

Skin pH: Why It Matters & How Products Affect It

Healthy skin pH is 4.5–5.5; this acid mantle regulates barrier enzymes, antimicrobial defense.

Skin Purging: What It Is, How Long It Lasts & Signs It's Not

Skin purging is a temporary breakout caused by actives accelerating cell turnover.

TEWL (Transepidermal Water Loss) Explained Simply

TEWL is the rate at which water passively evaporates through your skin.

What Is the Skin Microbiome & Why Does It Matter?

The skin microbiome is the community of bacteria, fungi.