Memorial Day, originally known as Decoration Day, is America’s most solemn holiday—one that remembers and honors the men and women who died while serving in the U.S. military.

In the United States, the tradition of Decoration Day began in 1868, three years after the Civil War ended, however the ancient Greeks and Romans held annual days of remembrance for loved ones (including soldiers) dating all the way back to 431 B.C.

The Civil War ended in 1865, claiming more than 620,000 lives—more than any conflict in U.S. history—the result of which required the establishment of the first national cemeteries. And by the end of that decade, various cities across the U.S. had begun holding tributes to the fallen soldiers, decorating their graves with flowers and flags.

Decoration Day originally honored only those lost while fighting in the Civil War, but after World War I the holiday evolved to commemorate American military personnel who died in all wars.

Today, many Americans observe Memorial Day by visiting cemeteries or memorials, and gathering together with family and friends. Cities across the U.S. host parades or memorials, often including military personnel or members of veterans’ organizations in the proceedings. And unofficially, it marks the beginning of the summer season, but truthfully, it is so much more than that.

In the year 2000, Congress passed legislation encouraging all Americans to pause for a National Moment of Remembrance at 3 p.m. local time. So while you head out today to commemorate the holiday in whatever fashion you wish, we encourage everyone to please pause at 3 p.m. and remember those who have fallen and honor them for making the ultimate sacrifice for our freedom.