Hair porosity describes how easily your hair absorbs and retains moisture. It's determined by the condition of the cuticle (the protective outer layer of each strand) and plays a major role in how your hair responds to products.
Low-porosity hair has a tightly sealed cuticle, making it slower to absorb moisture. Rich or heavy products can sometimes sit on the surface instead of penetrating the hair.
High-porosity hair has a more open cuticle, whether through genetics or damage from coloring, bleaching, or heat styling. It absorbs moisture quickly but loses it just as easily, making it more prone to dryness, frizz, and breakage.
Understanding your hair's porosity makes it easier to choose products that work with your hair rather than against it. It also helps explain why the same routine can deliver completely different results on different hair types.
