Nail fungus, also known as onychomycosis, is a common condition caused by fungal infections that affect the nails, particularly the toenails. It often leads to discoloration, thickening, and brittleness of the nails. The infection can occur when fungi enter through small cuts or separations between the nail and nail bed. Risk factors for developing nail fungus include a weakened immune system, diabetes, and poor circulation. It is more prevalent in individuals who frequently expose their feet to warm, moist environments, such as public swimming pools or locker rooms. Treatment options include antifungal medications and topical treatments, but prevention is key to avoiding recurrence.