Toenail: A toenail is produced by living skin cells in the toe. A toenail 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).
Toenails 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 toenail.
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. Toenails generally grow faster in young people, in males, and in the summer. Toenails grow more slowly than fingernails.
Ingrown toenails are common particularly on the big (great) toe. The corner of the nail curves down into the skin due to mistrimming of the nail or shoes that are too tight. An ingrown toenail can be painful and lead to infection.