Smoke and mirrors is a classic technique in magical illusions that makes an entity appear to hover in empty space. It was documented as early as 1770 and spread widely after its use by the charlatan Johann Georg Schröpfer, who claimed the apparitions to be conjured spirits. It subsequently became a fixture of 19th-century phantasmagoria shows. The illusion relies on a hidden projector (known then as a magic lantern) the beam of which reflects off a mirror into a cloud of smoke, which in turn scatters the beam to create an image.

The phrase "smoke and mirrors" has entered common English use to refer to any proposal that, when examined closely, proves to be an illusion. The earliest known use of the idiom came from the biography How the Good Guys Finally Won: Notes from an Impeachment Summer, published in 1975. It was written by American political journalist James Breslin, who accounted the Watergate political scandal in Washington first-hand. Breslin described politics as the theatrical use of "mirrors and blue smoke" to make people see what they wish to see.