Introduction
Pneumonia is swelling (inflammation) of the tissue in one or both of your lungs. It's usually caused by an infection.At the end of the breathing tubes in your lungs are clusters of tiny air sacs. If you have pneumonia, these tiny sacs become inflamed and swell up with fluid.
Terms such as bronchopneumonia, lobar pneumonia and double pneumonia are sometimes used, but refer to the same condition with the same causes and treatment.
