Ringworm most often begins as a red patch or small bump that develops into a ring or rings over time. The rings are normally raised and scaly, while the center of the rings remains clear, according to Kids Health.
It is called ringworm because of the appearance of the round ring-like rash it causes. When ringworm affects the nails, it causes discoloration and makes them thick and brittle, as Kids Health explains. Ringworm infections of the scalp can cause hair to fall out. Ringworm is caused by a fungal infection, not a worm. The same fungi also cause jock itch and athlete's foot; this category of conditions is called tinea.