A bonfire is a large controlled outdoor fire. The word is a contraction of "bone fire" (cf. for example "kostjor" in Russian - from "kost'" meaning "bone"). The practice is believed to derive from the Celtic festival of Samhain when animal bones were burnt to ward off evil spirits.
In Great Britain, bonfires are particularly associated with Guy Fawkes Night (also known as fireworks night or bonfire night), an annual commemoration of the discovery of the The Gunpowder Plot on 5 November 1605. In Sussex they are particularly associated with the execution of Protestant martyrs. In Northern Ireland, they are associated with celebrations on the anniversary of the Battle of the Boyne, which took place on 12 July 1690. Along with the Maypole, it is an important component of the Wiccan and Neopagan celebration of Beltaine, also known as May Day.
In the United States, a bonfire is often held at the end of a Homecoming rally. Bonfires may also be lit at campgrounds, at outdoor festivals, or to celebrate the end of an event or gathering such as a closing celebration of a Summer Camp session.