What nails are made of
Nails are made of keratin (KER-uh-tin), a tough protein. It's the same stuff that makes your hair and the top layer of your skin.
The hard part you can see is the nail plate. It's actually clear, but it looks pink because of the nail bed underneath, which is full of tiny blood vessels.
The white tip that grows past your fingertip is the part you trim.
Parts of a nail
Look at the bottom of a fingernail. You may see a pale half-moon shape. It's called the lunula (LOON-yuh-luh), which means little moon.
The lunula is the front edge of the nail root, called the matrix (MAY-triks). The matrix hides under your skin and makes new nail.
The thin strip of skin at the bottom of the nail is the cuticle (KYOO-tih-kul). It works like a seal that keeps germs from sneaking in under the nail, so it's best not to cut or pick it.
Not everyone can see a half-moon on every finger. Thumbs usually show it best.
How fast nails grow
Fingernails grow about 3 millimeters a month. That's about as thick as two pennies stacked up.
Toenails grow about half as fast. A whole new fingernail takes about 6 months to grow, but a whole new toenail can take a year or more.
Kids' nails grow faster than grown-ups' nails. Nails slow down as people get older.
Like hair, the part of the nail you can see isn't alive. That's why trimming your nails doesn't hurt.
Why we have nails
Nails protect the soft tips of your fingers and toes from bumps.
They help you pick up tiny things, like a coin or a bead, and they're handy for scratching an itch.
Nails help you feel, too. When you press your fingertip on something, the nail pushes back from behind, so the nerves in your fingertip get a better feel.
Lots of animals have claws or hooves made of keratin. People, apes and monkeys have flat nails instead.