Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Nail Diseases ?
    ### Response:
    Your toenails and fingernails protect the tissues of your toes and fingers. They are made up of layers of a hardened protein called keratin, which is also in your hair and skin. The health of your nails can be a clue to your overall health. Healthy nails are usually smooth and consistent in color.
    