Fingernails question?

Question

okay so im 13 and i bite my nails a lot and i just recently stoped like in this past week and i noticed that in my left hand on my finger nails i have this black like the runs vertical on my finger nails but they're not on my right hand but i bite both nails on each hand and i want to know what this black line could be?

help meee?!

Answer 1

bruise?

Answer 2

Those little black lines are hemmhorages (bleeding) under the nail bed, from biting your nails. They'll go away in time. Just don't bite anymore.

They aren't harmful.