Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) COPD ?
    ### Response:
    Chronic obstructive pulmonary disease, or COPD, is a progressive lung disease in which the airways of the lungs become damaged, making it hard to breathe. You may also have heard COPD called other names, like emphysema or chronic bronchitis. In people who have COPD, the airways that carry air in and out of the lungs are partially blocked, making it difficult to get air in and out.
    