"The Star-Spangled Banner" is the national anthem of the United States. The lyrics come from "Defence of Fort McHenry", a poem written in 1814 by the 35-year-old Maryland lawyer and amateur poet, Francis Scott Key, after witnessing the bombardment of Fort McHenry by the British Royal Navy ships in Chesapeake Bay during the Battle of Fort McHenry in the War of 1812. The poem was set to the tune of "To Anacreon in Heaven", a popular British song.
It is played at many official state functions both inside the United States and abroad. It was officially adopted as the US anthem in 1931.