Lung function refers to how well the lungs work to take in oxygen and expel carbon dioxide. It is measured through various tests that assess the volume of air the lungs can hold and how quickly air can be moved in and out. Healthy lung function is essential for overall well-being, as it supports the body's need for oxygen during activities. Factors affecting lung function include age, physical fitness, and environmental conditions. Conditions such as asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis can impair lung function, leading to difficulty in breathing and reduced oxygen supply to the body. Regular check-ups can help monitor and maintain lung health.