A pandemic is a global outbreak of new infectious diseases caused by the transmission of emerging and re-emerging pathogens that infect host species. The impact or severity of pandemics is often huge because many individuals lack pre-existing immunity to the new virus. The number of severe cases can increase drastically from endemic levels to that of a pandemic when a large portion of the global population becomes infected. Pandemics can have unusual epidemiological patterns, and large outbreaks may occur under specific conditions based on the nature of the virus. Both manmade and natural disasters can significantly intensify the risk of epidemics; however, pandemics are characterized by exclusive outbreaks with high fatality rates. Throughout history populations all over the world have sporadically faced devastating pandemic outbreaks. It has been observed that, every century, the outbreak of an epidemic caused by a specific virus tends to spread globally as a pandemic. In this context, this book highlights pandemics that have occurred over the centuries. It also examines specific epidemiological patterns and outbreak consequence scenarios across the world. The book aims to enrich the readers understanding of pandemics by providing valuable insights and knowledge on the preventive measures to be taken in response to pandemic.