Steam and smoke, most often produced by boiling water or with the aid of pyrotechnic devices, has been a fixture on theatre productions for centuries.
Well into the 1970s, paraffin or oil vapour was used to create smoke.
These techniques did not allow for precise controlling of smoke quantities, and the materials used, being flammable, were somewhat dangerous.
In the 1970s, Günther Schaidt developed the fog machine as we know it today.
This invention greatly improved the safety, ease, and precision of smoke and steam effects on theatre and other stages.