What Is Hair and How Does It Grow?


Hair is a protein-based biomaterial that grows from follicles in the dermis. It’s one of the most defining features of mammals, covering almost all surfaces except for areas of glabrous skin (like your palms, soles of feet and undersurfaces of your fingers and toes). It serves many functions in humans including insulation, camouflage, sexual recognition and attraction, and even signaling to other members of your species when you’re hungry or cold.

Each hair strand comes from a follicle, which is essentially a tiny, saclike hole in your skin. The follicle contains a cluster of special cells that reproduce to form new hairs. When the hair is fully grown, it emerges from the follicle as a filamentous outgrowth of the epidermis.

Depending on the type of hair you have, it may be coarse and wiry or fine and silky. It may also be straight, curly or wavy and have a bit of bounce or spring to it. Hair also varies in color, thickness and smell, which helps it identify itself among members of a certain species or serve other purposes like camouflage. In some animals, hair can also act as sensory organs, such as whiskers on a porcupine or quills on a rabbit.

There are two types of hair: vellus and terminal. The vellus hairs are the fine, downy hairs that grow all over the body and serve as insulation. The terminal hairs, found primarily on the head, armpits and legs, are coarser and darker in color and give you that little extra boost of confidence and self-assurance.

When you wash your hair, the shampoo you choose plays a big role in how your strands look and feel. For example, if you have oily hair and scalp, a clarifying formula that eliminates excess oil will be your best bet. “Oily hair often has a lot of build-up from products, so removing the excess oil will help balance out the natural oils,” says double board-certified dermatologist Dr. Wallace Nozile. Similarly, if you have dry hair and scalp, a hydrating shampoo can replenish the moisture your strands need to thrive.

As for how often to wash your hair, that’s a personal choice. Some experts recommend washing it everyday, while others suggest skipping it if you can. “Over-washing can strip the strands of their natural oils and cause them to over-produce these essential lipids, leading to dryness,” says celebrity stylist Jenny Shircore.

Whether your goal is to detangle, moisturize or smooth, there’s a shampoo out there for you and your hair texture. To help you navigate the shampoo aisle, we asked experts to share their top picks. Here are 26 of the best shampoos for every hair texture, style struggle and scalp concern, according to the pros.