The causes of the 1918 influenza pandemic stemmed from a combination of factors, including troop movements during World War I, urban overcrowding, and poor public health conditions. The H1N1 virus spread rapidly across the globe, resulting in an estimated 50 million deaths, making it one of the deadliest pandemics in history. The effects were profound, causing widespread social disruption, economic hardship, and overwhelming healthcare systems. Governments struggled to respond effectively, and a general atmosphere of fear permeated society. The pandemic eventually contributed to advancements in public health practices and policies, fostering greater awareness of infectious diseases and the importance of global cooperation in health crises.