This book will guide readers through the history of the flu. In ten chapters, it explains Influenza in a simple way. Influenza always seems to have endless topics. The flu virus, seemingly tiny, has brought on one disaster after another to human beings. 2018 is the 100th anniversary of the outbreak of the "1918 Flu" that swept the world. The flu, a century ago, claimed nearly one-twentieth of human life on the planet. It became the most deadly flu in human history. This book introduces the past and present life of the influenza virus in a light-hearted way, leading the reader to review the past from the history of the flu, the development of the flu, human immunity and health, impacts on society and the country. Through touching stories, illustrations and diagrams, it tells the great discoveries and related advances in science and technology, introduces medical knowledge related to influenza, and reviews the medical effectiveness in preventing influenza, thus displaying the ongoing battle between humans and the flu virus. Looking back at the development of science and technology, humans have relentlessly sought the prevention and control of this infectious disease, constantly guarding the path of life and health, which gradually becomes a quiet past, but only to awaken again and again.