The lung is a vital organ in the respiratory system responsible for gas exchange. Humans typically have two lungs, located in the chest cavity, which help take in oxygen from the air and expel carbon dioxide. The lungs are made up of millions of tiny air sacs called alveoli, where this exchange occurs. Lungs are protected by the rib cage and are surrounded by a membrane called the pleura. They work closely with the diaphragm, a muscle that aids in breathing by contracting and relaxing to allow air in and out. Proper lung function is essential for overall health and well-being.