If you look at your finger nails, u generally see that the color of the nails are clear, where as the
part that grows is white. whu??
You skin is pressed tight against the nail and therefore it shows thru clearly. The ends of nails appear white because of the light behind them. This is something like the pressing of body parts against a shower door and such parts being more apparent.
Although images of body parts pressed against a shower door are quite amusing, I think eyedea is refering to the lunula, the cresent shape of white at the base of the fingernail.
The lunula is white because the nail matrix is white.
Cool nail word of the day: hyponychium.