This document discusses pneumothorax, which is the presence of air in the pleural space. It can be spontaneous, due to underlying lung disease or trauma, or iatrogenic due to medical procedures. The types are described as closed, open, or tension pneumothorax. Clinical features include chest pain and breathlessness. Diagnosis is made through chest x-ray or CT scan. Treatment depends on the type and severity, ranging from needle aspiration for minor cases to chest tube drainage or surgery for more severe or recurrent cases.