What is "service flag"

A service flag or service banner in the United States is an official banner that family members of service members can display. The flag or banner is defined as a white field with a red border, with a blue star for each family member serving in the Armed Forces of the United States during any period of war or hostilities in which the Armed Forces of the United States are engaged. A gold star (with a blue edge) represents a family member that died during service, regardless of cause of death. The deceased might have been killed in action, or died due to unrelated causes.