The 1918 influenza pandemic, also known as the Spanish flu, was a global outbreak of influenza that occurred between 1918 and 1919. It infected about one-third of the world's population and resulted in an estimated 50 million deaths worldwide. The virus spread rapidly due to troop movements during World War I and the lack of effective vaccines or treatments at the time. The pandemic had a significant impact on public health systems and led to increased awareness of the importance of hygiene and disease prevention. It also influenced future pandemic preparedness and response strategies, shaping how health organizations manage outbreaks today.