The Bat-Signal is a fiction device appearing in the various interpretations of the Batman mythos. It is a specially modified Klieg searchlight with a stylized symbol of a bat attached to the light so that it projects a large Bat emblem on the sky or buildings of Gotham City. In the stories, the signal is used by the Gotham City Police Department as a method of contacting and summoning Batman to their assistance in the event of a serious crisis.
The origin of the signal varies between timeline and media. In the 1989 Batman film, Batman gave the signal to the police as a gift enabling them to call him when the city is in danger; in 2005's Batman Begins, then-detective James Gordon creates his own signal light, inspired by an incident when Batman strapped the defeated mobster Carmine Falcone to a large searchlight which created a roughly bat-like image from the light's beam. In the comic's post-Crisis continuity the signal was introduced after the Batman's first encounter against the...
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