The toenail fungal disease is an infection which is triggered by live fungi inside, on and near the nail. The nail might be of finger or toe, hands or legs. Fungus grows in dark and moist place and it loves wet atmosphere to live and also to spread. The nail is a hard building with small other structures surrounding it like nail beds, cuticles etc. The nail is directly attached with the skin but then too, there is very micro-space in between them. The fungus locates this as the right location to maintain and also to grow as after washing, those micro-spaces stay wet and moist.