Gray nail is the common name given by the common people to the fungal infection of the nails. Of course, fungal infections of the fingernails and toenails are called gray nails by the common people. At first, it was thought that when the nails were infected with fungus, the nails would appear dirty yellow with furry scales underneath, and the nails would be thickened, so it was commonly known as gray nails. But clinically, the fungal infection of the nails will also be manifested as white, that is, the nails are white, some are white at the distal end, and some are white at the root of the nails, so there are various manifestations of gray nails.