Swine Flu, officially known as H1N1 influenza, is a respiratory illness caused by the H1N1 influenza A virus. The virus originated in pigs but can be transmitted to humans, leading to outbreaks of influenza with human-to-human transmission. The H1N1 strain gained global attention during the 2009 pandemic, which marked the first influenza pandemic of the 21st century. The virus exhibits a combination of genetic material from swine, avian, and human influenza viruses. Clinical features of Swine Flu are similar to those of seasonal influenza, including fever, cough, sore throat, body aches, and fatigue. In severe cases, respiratory distress and pneumonia can occur, leading to hospitalization and, in some instances, death. Certain populations, such as pregnant women, young children, and individuals with underlying health conditions, are at a higher risk of severe complications. The 2009 H1N1 pandemic prompted a coordinated global response. Vaccination campaigns were initiated, antiviral medications were administered, and public health measures focused on reducing transmission through hygiene practices and social distancing. The experience with the H1N1 pandemic has informed subsequent influenza preparedness and response strategies worldwide.