Onychomycosis is a fungal infection that affects the nails, commonly seen in both fingers and toes. It is characterized by changes in the nail's appearance, such as discoloration, thickening, and brittleness. The infection can be caused by various types of fungi, including dermatophytes, yeasts, and non-dermatophyte molds. Treatment for onychomycosis often involves antifungal medications, which can be applied topically or taken orally. In some cases, nail removal may be necessary to fully eliminate the infection. Maintaining good foot hygiene and keeping nails trimmed can help prevent the occurrence of onychomycosis.