Memorial Day is a United States federal holiday which occurs every year on the final Monday of May. Memorial Day is a day of remembering the men and women who died while serving in the United States Armed Forces. Formerly known as Decoration Day, it originated after the American Civil War to commemorate the Union and Confederate soldiers who died in the Civil War. By the 20th century Memorial Day had been extended to honor all Americans who have died while in the military service. It typically marks the start of the summer vacation season, while Labor Day marks its end.