Patriot Day is an annual observance on September 11 to remember those who were injured or died during the terrorist attacks in the United States on September 11, 2001. Many Americans refer to Patriot Day as 9/11 or September 11.
Patriot Day should not be confused with Patriot's Day also known as Patriots Day, which commemorates the battles of Lexington and Concord in 1775, which were two of the earliest battles in the American Revolutionary War.