Chronic Obstructive Pulmonary Disease (COPD) is a preventable and treatable disease that makes it difficult to empty air out of the lungs. This difficulty in emptying air out of the lungs (airflow obstruction) can lead to shortness of breath or feeling tired because you are working harder to breathe. COPD is a term that is used to include chronic bronchitis, emphysema, or a combination of both conditions. Asthma is also a disease where it is difficult to empty the air out of the lungs, but asthma is not included in the definition of COPD. It is not uncommon, however for a patient with COPD to also have some degree of asthma.