The infectious diseases caused by influenza viruses are termed as influenza. Symptoms of influenza generally begin after 1-4 days of exposure to the virus and last for 2-8 days. They include runny nose, sore throat, fever, headache, muscle pain, fatigue and coughing. In children, diarrhea and vomiting may also occur. The progression of influenza may cause pneumonia. It can be caused by a primary viral infection or a secondary bacterial infection. Other complications of influenza are worsening of pre-existing health problems such as asthma and cardiovascular diseases, and diseases such as meningitis, acute respiratory distress syndrome and encephalitis. Influenza viruses are classified into 4 types, namely, an influenza virus A, B, C, and D. This book unfolds the aspects of diagnosis and management of influenza. It unravels the recent studies in this field. The extensive content of this book provides the readers with a thorough understanding of the subject.