Hair types are commonly grouped into four categories based on natural curl pattern: straight wavy, curly and coily. Knowing your pattern can help you choose products and styling methods that work better with the way your hair naturally behaves. Thickness, porosity and hair condition also affect what your hair needs.[1]
What Are Hair Types?
Hair type describes the pattern your hair forms as it grows. Some strands fall straight from the scalp while others develop waves, curls or tighter coils. The shape and structure of the hair follicle play a role in determining that pattern. Hair begins forming inside the hair follicle, where cells produce and organize the developing hair fiber. Differences, in hair follicle shape, curvature and the way cells develop within the growing hair can contribute to whether the finished strand's straight wavy, curly or tightly coiled
Most hair-care guides use four categories:
Each category includes several subtypes. For example wavy hair can range from a barely noticeable wave to a more defined S-shaped pattern. Your hair can also have more than one pattern. Some areas may be straighter while others are wavier or curlier around the crown, hairline or back of the head.
The Four Main Hair Types
Type 1: Straight Hair
Straight hair generally falls from the roots without forming a wave or curl. It can have an appearance and may reflect light easily. Straight hair comes in thicknesses. Fine straight hair can become weighed down by creams and oils while thicker straight hair may handle richer conditioning products more easily.
Type 2: Wavy Hair
Wavy hair forms a S-shaped pattern. Some Type 2 hair has waves that begin closer to the roots while other hair stays straight at the top and becomes wavier toward the ends. Lightweight conditioners, leave-in products and styling creams can help define waves without making them feel heavy. Brushing the hair excessively after it dries can also disturb the wave pattern. Increase frizz.
Type 3: Curly Hair
Curly hair forms defined loops or spirals. The curls can vary considerably in size within the same head of hair. The bends and twists in a strand can make it harder for natural scalp oils to travel from the roots all the way to the ends. Because of this curly hair tends to be more likely to feel dry. The many curves can also cause rubbing and physical pressure on the strand, which can lead to breaking when the hair is not handled carefully.[2] Regular conditioning, detangling and reducing excess friction can help keep curls manageable and reduce breakage.
Type 4: Coily Hair
Coily hair forms curls, coils or bends. The pattern may look spring-like, zigzagged or tightly curled. This hair type can be more vulnerable to dryness and mechanical damage so gentle handling is especially important. Moisturizing conditioners, leave-in products and careful detangling can help keep the hair manageable.
Why Does Hair Grow Curly?
The shape of a hair strand starts to form while the hair is still growing inside the follicle. Research on hair shows that the follicles structure and curvature shape how the hair fiber forms. In hair the follicle can be curved. Differences in how cells grow inside the hair-forming area also help decide the shape of the hair strand. The cross‑section shape of the hair fiber can also matter.[3]
“Genetics also shape hair features, which is why natural hair patterns often run in families.”
The pattern can change across a person's scalp. A person might have waves near the front, tighter curls at the back or parts that look straighter because of differences in growth, damage, styling or because the individual follicles produce different strands. That variation is completely normal.
Hair Thickness and Density
Hair type tells you about the pattern of each strand. Hair thickness and Hair density describe characteristics with
- Hair thickness refers to how thick a single strand is.
- Hair density refers to how many strands grow across a spot on the scalp.
This means one person can have dense curly hair while another person can have thicker curls with lower density. Two people, with the curl pattern can therefore look very different and need different products. You might notice that fine hair can feel weighed down while thicker or coarser hair can benefit from richer conditioning.
What About Hair Porosity?
Porosity tells you how easily a hair shaft takes in and keeps moisture. Hair with porosity takes in water and products quickly. Hair with porosity takes longer to soak up moisture.[4] Please remember, porosity is not the same as hair thinning. Porosity shows how the hair shaft behaves. Hair thinning means changes in hair growth, more shedding or follicles not producing hair properly. Thickness and density are separate from porosity too. You can have hair that's low in porosity or thick hair that is high in porosity. If you see shedding, a part that spreads wider or a clear drop, in density you should look at that issue separately from hair type or porosity.
How to Choose Products Based on Your Hair Type
Start with your hair pattern then consider what your hair feels and looks like after washing. Straight and fine hair may benefit from shampoos, conditioners and styling products that provide softness without excessive weight. Wavy hair often responds well to lightweight moisture and products designed to enhance definition. Curly and coily hair may benefit from conditioners and leave-in products that make detangling easier and help reduce friction during styling. The ingredients matter, too. Conditioning agents can help smooth the hair surface while humectants such as glycerin can attract water. Oils and other emollient ingredients can add softness. Reduce the rough feel associated with dryness.[5] If your hair is colored, chemically treated, frequently heat-styled or damaged, those factors should also influence your product choices. Understanding what your hair needs can help you create a routine that really works. If you are worried about hair thinning or shedding RE:YOU's Dual-Path Hair Revival Serum has NOVOGRO™ molecules. These molecules are made to support the hair follicles and the area around them. The serum is light and water-based so it fits right into a scalp-care routine.
Common Hair-Care Mistakes
One common mistake is buying products based entirely on a hair-type label. A product marketed for hair for example may still feel too heavy for someone with fine curls. Another is using too many products. Applying an amount does not necessarily produce better results. Start with an amount and add more when needed. Aggressive brushing and frequent heat styling can also contribute to breakage. Wet hair is particularly vulnerable to damage from handling so detangle gently and avoid pulling through knots. It is also worth reassessing your routine. Hair can behave differently after coloring, cutting, growing longer, changing the climate or using heat and chemical treatments frequently.
The Main Takeaway
Hair types are a place to start when creating a hair-care routine. The thickness of each strand, how full the hair is, how well it holds moisture and the current condition of the hair all influence which products and methods are most effective. Healthy hair also relies on healthy follicles because every single strand comes from a follicle on the scalp. Caring for the scalp and staying away from pressure or pulling can help encourage healthy hair growth.
References
[1] How to Identify and Style Your Hair Type
[2] 6 Curly Hair Care Tips from Dermatologists
[3] In Brief: What Is the Structure of Hair and How Does It Grow?
[4] What Type of Hair Porosity Do You Have?
[5] On Hair Care Physicochemistry: From Structure and Degradation to Novel Biobased Conditioning Agents