Nail

A nail is a hard, keratinous structure that emerges from the upper surface of the fingertip or toe. It is made of keratin, a hard protein also found in hair and the outer layer of skin. Nails are characteristic features of mammals, particularly humans, primates, and some other animals; other animals produce analogous structures such as claws or hooves.

The functions of nails include protection of the sensitive skin beneath the fingertip, support for the sense of touch, and assistance with fine motor tasks such as writing, scratching, and grasping small objects. Nails also serve as a health indicator; changes in color, shape, or growth rate can sometimes signal underlying health conditions.

Structure

A nail consists of several parts. The nail plate is the visible, hard portion. The nail bed is the skin underneath, to which the plate is attached. The matrix, located in the tissue beneath the nail, is where new cells are generated and where growth begins. The pale crescent-shaped area at the base of the nail in many people is called the lunula. The skin surrounding the nail at the sides protects against bacteria and fungi.

Growth

Nails grow continuously throughout life, as new cells are generated in the matrix and old cells are pushed forward. Fingernails generally grow faster than toenails. Growth rate is influenced by age, diet, environmental temperature, and health status. If the matrix is damaged, the nail may emerge deformed or fail to grow back.

Diseases and Conditions

Common conditions include nail fungus (onychomycosis), which causes thickening and discoloration; infection beneath the nail, most often affecting the large toe; and injuries or irritation from chemical exposure. Skin diseases such as psoriasis cause pitting or separation of the nail. Trauma to the nail can result in subungual hematoma, bleeding under the nail.

Culture and Care

Nails are treated and beautified through various practices: cutting, filing, painting, and artificial nails. The nail care industry (manicure and pedicure services) is a large global market. From a health perspective, regular nail trimming, hygiene maintenance, and avoidance of shared tools are recommended to prevent fungal infection.