Our nails serve many important roles. They protect and support tissue in our fingers and toes. Having nails allows us to scratch an itch. A look at your nails can warn a doctor of underlying medical conditions such as heart disease or diabetes.
Basically, nails are hardened skin cells composed largely of keratin, a protein found in the skin and hair. Fingernails grow from the matrix (the hidden half-moon area under the cuticle), and as new skin cells grow in the matrix, the older cells are pushed forward, where they harden and form a visible nail.
How fast a nail grows largely depends on several factors: Nails grow faster in summer than winter. Men’s nails grow more quickly than women’s, except possibly during pregnancy and old age. The nails on a person’s dominant hand grow faster. On average, fingernails grow 2 to 3 millimeters per month, while toenails grow 1 millimeter per month. Disease, hormone imbalance, and aging are causes of slow nail growth.