Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Back Pain ?
    ### Response:
    If you've ever groaned, "Oh, my aching back!", you are not alone. Back pain is one of the most common medical problems, affecting 8 out of 10 people at some point during their lives. Back pain can range from a dull, constant ache to a sudden, sharp pain. Acute back pain comes on suddenly and usually lasts from a few days to a few weeks.
    