By presidential proclamation, Patriot Day is observed in the United States on September 11, or 9/11, in memory of the thousands who lost their lives as a result of the September 11, 2001, terrorist attacks against the United States that involved four hijacked planes. The observance also honors those who came to aid in the aftermath. Each year on Patriot Day, the U.S. flag is flown at half-staff. Citizens are asked to observe a moment of silence, usually at 8:46 a.m. EDT (when the first hijacked plane struck the World Trade Center in New York City), and are encouraged to devote the day and year to serving their neighbors and communities.

FROM WIKIPEDIA COMMONS

OBSERVANCE

The flag of the United States is flown at half-staff at the White House and on all U.S. government buildings and establishments throughout the world; Americans are also encouraged to display flags in and outside their homes. Additionally, a moment of silence is observed to correspond with the attacks, beginning at 8:46 a.m. (Eastern Daylight Time), the time the first plane, American Airlines Flight 11, struck the North Tower of the World Trade Center on September 11, 2001.

Patriot Day is not a federal holiday; schools and businesses remain open in observance of the occasion, although memorial ceremonies for the 2,977 victims are often held. Volunteer and service opportunities are coordinated by the Corporation for National and Community Service.