http://www.nhlbi.nih.gov/health/dci/Diseases/pnu/pnu_whatis.html
National Heart, Lung, and Blood Institute, National Institutes of Health
Pneumonia (nu-MO-ne-ah) is an infection in one or both of the lungs. Many small germs, such as bacteria, viruses, and fungi, can cause pneumonia. The publication links to more information about the infection, including types, causes, signs and symptoms, diagnosis, treatments, and prevention.