Flags are flown at half mast (or half staff) as a symbol of respect, mourning, or distress. This tradition is followed to honor notable deaths, national tragedies, or days of remembrance such as Memorial Day or after the death of a government official or military member. The flag is lowered to about halfway down the pole to visually signify mourning or solemn respect. The practice originated centuries ago, possibly to make room for an "invisible flag of death" above the flag, and it has been formalized in flag protocol in many countries. In the U.S., the President or state governors can order flags to be flown at half staff in specific circumstances, including the death of prominent leaders or major national tragedies. Thus, if flags are seen flying at half mast today, it generally means the nation or community is observing a moment of mourning or respect for someone who has passed away or in response to a somber event.