vellus

Vellus, also known as down hair, refers to the fine, short, and unpigmented hairs that grow on most of the body's surface, except for specific areas like the palms and soles. These hairs develop in infancy and cover the body until puberty. At puberty, vellus hair is often replaced or supplemented by longer, coarser, and more pigmented terminal hair in areas such as the armpits and genital regions.1

In males, terminal hair also grows on the face, forming a beard, and sometimes on the trunk and limbs. The term "peach fuzz" specifically describes the fine facial hair that appears on adolescent males. Mammalian hair, in general, serves crucial functions like insulation against cold, camouflage, and sensory perception through specialized hairs called vibrissae. Each hair grows from a follicle within the skin and is composed primarily of keratin.213