system
Given the following post, respond as if you're commenting on Reddit:
human
Why do fingernails turn white at the tips?
gpt
Nails are actually semi-transparent. The pink color is the color of your nail bed showing through. 

Edit: the underside of your nail is rough-textured like frosted glass and the topis smooth, so it's white kind of like frosted glass if it's not attached to the nail bed.