"Memorial Day is our day of remembrance of those men and women who died in service to our country. It was originally known as Decoration Day because it was a time set aside to honor the nation’s Civil War dead by decorating their graves. The first known observance was in Waterloo, N.Y. on May 5, 1866. (In fact, in 1966, President Lyndon Johnson proclaimed Waterloo as the official birthplace of Memorial Day)

In 1971, Congress declared Memorial Day a national holiday, to be recognized on the last Monday in May. Today, Memorial Day is observed at Arlington National Cemetery with a ceremony in which a small American flag is placed on each grave. Also, it is customary for the president or vice-president to give a speech honoring the contributions of the dead and lay a wreath at the Tomb of the Unknown Soldier.

. On Memorial Day the flag is raised briskly to the top of the staff and then solemnly lowered to the half-staff position, where it remains only until noon. It is then raised to full-staff for the remainder of the day. The half-staff position remembers the more than one million men and women who gave their lives in service of their country. At noon their memory is raised by the living, who resolve not to let their sacrifice be in vain, but to rise up in their stead and continue the fight for liberty and justice for all."

-- http://www.history.com