The Orange Order is a Loyalist fraternal organization found in 1795 in Loughgall, County Armagh, after the Battle of the Diamond.
It uses two flags:
The first flag is orange and has a purple star in the middle. The orange is for William of Orange the Protestant prince who defeated the Catholics in the Battle of the Boyne in 1690 and has been a symbol for Protestants since. The purple star was a symbol of Williams forces.
The second flag also has the orange background and a smaller purple star on the lower right side, but on the upper left quadrant contains the Cross of Saint George.
Now that you know all about this flag, why don't you read about the other unofficial flags of Northern Ireland?