Fungi (the plural of fungus) are tiny, microscopic organisms that cause a fungal nail infection. Nail fungus is a common infection of the nail that begins as a white or yellow-brown spot under the tip of the fingernail or toenail. As the fungal infection goes deeper, the nail may discolor, thicken and crumble at the edge. Nail fungus can affect several nails. 

How do you pick up the fungi? Often, it’s through skin-to-skin contact with someone who has a fungal infection, or by walking barefoot in a warm, moist area such as a pool deck or locker room. You can even get a fungal nail infection by sharing an infected nail clipper or towel. You can also get it if your nails are frequently moist or you often wear sweaty socks and shoes.