A fingernail is produced by living skin cells in the finger. A fingernail consists of several parts including the nail plate (the visible part of the nail), the nail bed (the skin beneath the nail plate), the cuticle (the tissue that overlaps the plate and rims the base of the nail), the nail folds (the skin folds that frame and support the nail on three sides), the lunula (the whitish half-moon at the base of the nail) and the matrix (the hidden part of the nail unit under the cuticle).
Fingernails grow from the matrix. The nails are composed largely of keratin, a hardened protein (that is also in skin and hair). As new cells grow in the matrix, the older cells are pushed out, compacted and take on the familiar flattened, hardened form of the fingernail.
The average growth rate for nails is 0.1 mm each day (or 1 centimeter in 100 days). The exact rate of nail growth depends on numerous factors including the age and sex of the individual and the time of year. Fingernails generally grow faster in young people, in males, and in the summer.
Fingernails grow faster than toenails. The fingernails on the right hand of a righthanded person grow faster than those on their left hand, and vice versa.