Hair Explained: Structure, Growth Cycle, Types and Care Facts for Indian Readers

Search interest in "Hair" has been rising in India — Google Trends data observed on 13 October 2026 shows the term growing 40% over the past 12 months. That signal reflects curiosity, not a news event, so this explainer answers the questions behind those searches: what hair is actually made of, how fast it grows, why it turns grey, and what dermatologists say about hair loss and everyday hair care facts.

What hair is made of

Hair is a protein filament that grows from follicles in the dermis, the deeper layer of skin. It is composed mainly of a protein called alpha-keratin, and it is one of the defining characteristics of mammals. The word "hair" actually covers two structures: the follicle (or root) beneath the skin, and the shaft — the hard filament that extends above the surface.

A key fact many people miss: the visible hair is dead. The only living portion sits inside the follicle, where the bulb at the base contains the cells that produce the shaft. Each strand has three layers:

• Cuticle — the outer covering of overlapping flat cells, like roof shingles.
• Cortex — the middle layer that provides mechanical strength and holds melanin, the pigment that gives hair its colour.
• Medulla — an unstructured innermost region that is not always present.

Natural colour comes from two melanin types: eumelanin dominates in brown and black hair, while pheomelanin dominates in red hair. Grey hair appears when melanin production decreases or stops.

How fast does hair grow?

Hair grows in a repeating cycle of three phases — anagen (growth), catagen (transition) and telogen (resting) — and each strand is at its own stage. According to MedlinePlus, healthy hair takes about a month to grow half an inch, and most hairs grow for up to six years before falling out and being replaced. Research summarised on Wikipedia's hair article puts scalp hair growth between 0.6 cm and 3.36 cm per month, varying with age, genetics and strand thickness — thicker hair generally grows faster than thinner hair.

The average person has about 5 million hairs across the body, growing everywhere except the lips, palms and soles. Hair is not just cosmetic: it helps keep you warm and protects your eyes, ears and nose from small airborne particles.

Hair types and texture

Whether hair is straight, wavy or curly depends on the shape of the follicle and the fibre's cross-section — round fibres tend to be straight, while flatter or oval fibres are wavier or curlier. The widely used Andre Walker system classifies hair into four types: straight (Type 1), wavy (Type 2), curly (Type 3) and kinky/coily (Type 4), each with sub-categories based on fineness. Knowing your type matters because care needs differ — tightly coiled hair, for instance, has fewer cuticle layers and is more prone to damage, while straight hair lets scalp oil travel easily to the ends.

Common problems: hair loss, infections and flaking

MedlinePlus lists hair loss, infections and flaking as the most common hair and scalp problems. For hair loss specifically, the American Academy of Dermatology's Hair Loss Resource Center offers dermatologists' insight into causes and treatments. One practical warning from the AAD: weaves and extensions can damage natural hair and even cause hair loss if proper precautions are not taken — relevant for anyone using them regularly. Persistent or sudden hair fall is best assessed by a qualified dermatologist rather than self-treated with unverified products.

An Indian world record

India holds a notable place in hair history: Smita Srivastava of Uttar Pradesh set the Guinness World Record for the longest hair on a living person in November 2023, at 7 feet 9 inches, after growing her hair for 32 years.