Memorial Day in the United States commemorates the men and women who died while serving in the U.S. military. Observed on the last Monday of May, it began after the Civil War as a way to honor Union soldiers who had fallen. Over the years, it has evolved to honor all military personnel who have lost their lives in service to the country across various conflicts. Memorial Day is marked by memorial services, parades, and the decoration of graves, particularly at national cemeteries. It serves as a solemn reminder of the sacrifices made for national freedom and security.