Explanation

Fingernails and toenails are made of a tough protective protein called alpha-keratin. This protein is also found in the hooves and horns of different animals. 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.