A black line on your nail (medically known as melanonychia) causes a streak of dark pigmentation that runs along the nail bed ...

White spots can also be the result of repeated trauma to the nail bed — this means that getting manicures too often can cause spots, even if there isn't a significant injury, says Engelman.

called the nail bed. Photo credit: iStock/Getty Images It’s easy to ignore fungal nail infections at first, since you may not have any pain. But if you don’t treat them, it can hurt to put any ...