4 Types of Hair (Plus Thick vs. Thin Hair, Porosity and More) (2025)

Hair is one of the most expressive parts of our bodies. It's a living record of our genetics, our environment and even what we had for lunch (hello, greasy roots). With all the diversity in the world, how do we begin to categorize the many types of hair out there?

Scientists, hairstylists, and beauty enthusiasts have tried to break down hair characteristics into understandable buckets. These categories consider everything from curl pattern to hair density to how your hair behaves on a humid day.

So let's take a look — strand by strand — at what makes each hair type unique.

Contents

1. Straight Hair
2. Wavy Hair
3. Curly Hair
4. Coily Hair
5. Fine, Medium and Coarse Hair
6. Hair Subtypes
7. Thick vs. Thin Hair
8. Hair Porosity
9. Natural Hair
10. Hair Color

Straight hair, especially pin-straight hair, lies flat from root to tip because of the follicle's shape and angle. It's often shiny because the outer layer reflects light well.

But straight hair can be prone to excess oil and product buildup since oil travels easily down the hair shaft. Dry shampoo and lightweight styling products are essential for your haircare routine if you fall into this category.

Wavy hair has a natural S-shaped bend that varies widely in intensity. It's like the midpoint between straight and curly. This hair texture can be fine or medium, making it versatile but sometimes unpredictable.

Wavy hair thrives with moisture-balanced hair care products and styling techniques that enhance its natural shape without weighing it down.

Curly hair features distinct loops or ringlets. This hair type can include loose curls or tight curls and tends to have more volume and a natural curl pattern.

The individual hair strand in curly hair tends to be more porous, requiring more moisture and care to avoid a frizzy mane. Using a heat protectant and steering clear of heavy serums can help maintain healthy hair.

Coily or kinky hair has a zig zag pattern or tight corkscrew curls that form a dense hair structure. Often considered the most fragile due to its tight curl pattern, this hair type demands extra TLC.

Protective styles, moisturizing treatments, and avoiding product buildup are key for maintaining your natural curls in their healthiest state.

These labels describe the thickness of a single strand of hair.

Fine hair has a smaller diameter and can look flat, while medium hair has more body. Coarse hair is the thickest and most resilient, but can be prone to dryness.

Each category affects how your hair reacts to styling products and environmental factors. For example, coarse hair might need more moisture, while fine hair can be overwhelmed by heavy products.

Within each broad hair type, there are subtypes categorized from 1A (pin-straight) to 4C (very tight curls). These subtypes help narrow down your hair's characteristics like curl definition, volume and how it reacts to humidity.

Thick and thin hair refer to hair density (the number of hair strands on your scalp). You can have fine, coarse or medium hair texture and still have either thick or thin hair overall.

Thick hair looks full but can take longer to dry and might need strong hold styling products. Thin hair, on the other hand, benefits from volumizing sprays and should steer clear of heavy serums that weigh it down.

Hair porosity refers to your hair's ability to absorb and retain moisture. High-porosity hair absorbs moisture quickly but may lose it just as fast. Low-porosity hair resists moisture but retains it well once absorbed.

Understanding your porosity helps you tailor your hair care for healthy hair outcomes — think less product buildup and better hydration.

Natural hair refers to hair that hasn’t been chemically straightened, curled or colored. It includes curly, coily, wavy and straight textures in their natural state.

Embracing natural hair means paying attention to your natural curl pattern, using the right hair care products and adopting a haircare routine that maintains the health of each strand of hair.

Whether you have blonde hair or are sporting a bold hue, hair color is more than just aesthetics. It can affect hair texture, especially if you've dyed your hair.

Color-treated hair often requires extra conditioning to reduce damage, preserve pigment and maintain elasticity. The cuticle layer of hair benefits from protection against heat tools and UV exposure, both of which can degrade structural proteins and pigment.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.