The fingernail is continuously formed at the root of the nail from the so-called nail matrix. The cells formed in the nail matrix move to the front edge of the nail within three to six months.
During this time, they store keratin, die and harden to form the closed nail body. Fingernails grow about 1mm per week, which is about four times faster than toenails, which take about one month to grow this amount. Nail growth is very individual and depends on age, nutrition, living circumstances and mechanical stress.
Healthy fingernails have no grooves or stains, they are hard but flexible. Dull, brittle and splintering fingernails, on the other hand, could be an indication of a vitamin or mineral deficiency.