This article provides an overview of pneumonia as a high-incidence respiratory disease of varying severity in the 21st century. Many cases are mild to moderate and patients are successfully treated with antibiotics at home and with no lasting damage to the lungs. Vaccinations for influenza and, more recently, pneumococcal infections are becoming widely available for vulnerable groups of people, which will help to reduce the incidence of these diseases. However, pneumonia causes death in more severe cases with atypical forms such as Legionnaires’ disease and severe acute respiratory syndrome (SARS) causing fatal outbreaks.