We have approximately 5 million hair follicles on our body, of which 100,000 are located on the scalp. Vellus hair is tiny and colourless, covering most of our body, while thicker pigmented ones are called terminal hair. Examples of terminal hair are those located on the scalp, eyebrows, eyelashes, pubis and armpits.
Hair growth occurs in a cycle, and its duration varies according to where they grow on our body. Scalp hair goes through 2 to 6 years of an active growth phase (anagen phase), followed by 1-2 weeks of a transition phase (catagen phase), and finally 2 to 4 months of a resting phase (telogen phase). 80% to 90% of our hairs are in the anagen phase and 10% to 15% of our hairs are in the telogen phase at a given point in time. Each hair follicle independently undergoes the cycle at different times, if not, our hair would shed all at once! When this proportion is altered, you may notice some hair loss or thinning.