Pneumonia is an acute lower respiratory tract infection associated with fever, symptoms and signs in the chest and abnormalities on the chest X-ray. Community-acquired pneumonia (CAP), the most common and serious form of pneumonia and illness is defined as the presence of symptoms and signs, which are consistent with an acute lower respiratory tract illness associated with new radiographic shadow for which there is no other explanation in a patient who has not recently been hospitalized. Risk factors for CAP are age, active smoking, obesity and at least in women, a sedentary lifestyle. S. pneumoniae is the single most common pathogen in causing CAP. However, when CAP is severe, the patient needs to be referred at the earliest to the concerned specialist/consultant for appropriate treatment in hospital in order to ensure a successful outcome. Fungal infection is another common disease that can be caused by T cell opportunists and phagocyte opportunists. Various fungal infections include aspergillosis, extrinsic asthma, candidiasis, histoplasmosis, blastomycosis, cryptococcosis, nocardiosis, etc. Prevention of exposure, immunization and antiviral prophylaxis are the three major steps to prevent viral pneumonia, which is mainly caused by respiratory syncytial virus, varicella zoster virus, and influenza viruses A and B, cytomegalovirus, parainfluenza viruses 1-4, herpes simplex virus type 1, human metapneumovirus, measles virus, rhinoviruses, human bocaviruses and Hantaviruses.