Vital capacity is the maximum amount of air a person can exhale after taking a deep breath. It is an important measure of lung function and overall respiratory health. Vital capacity is typically measured in liters and can vary based on factors such as age, gender, and physical fitness. This measurement is often assessed using a device called a spirometer. By understanding vital capacity, healthcare professionals can evaluate conditions like asthma or chronic obstructive pulmonary disease (COPD) and monitor a patient's lung health over time.