system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does our fingernails have faint lines going up and down?
gpt
well first you should know that its normal. Evenly spaced vertical lines are never a sign of a problem (But horizontal lines, you should see a doctor.)

What happens is that as you get older, parts of the nail matrix (the part of your fingers that the nail grows out of) atrophy. They become weak and dont function quite as well.  This results in the increasingly prominent vertical ridges.

They're very similar in this way to skin wrinkles. Just the natural result of the aging process.