Overview
The reveal (also known as the big reveal) is a plot device in narrative structure and is the exposure to the reader or audience of a previously unseen key character, or element of plot or performance.
A reveal is different from Aristotle's anagnorisis, in which something is revealed to a character rather than to the audience.
Narrative
The reveal may result in a plot twist and could be the key plot turn or unexpected coda in the story; for example, in the mystery genre. It may have scenes in the future that reveal consequences of actions to provide a lead for what will occur in the plot or side plot. This may be the overarching plot line in a mystery or soap opera. It may also be used as a device (particularly in the climax) in stage magic by an illusionist or escape artist.
Stage magic
In a magician's act, "the reveal" may refer to
the normal culmination of a trick
the unexpected (to the audience) culmination of the trick
an explanation of the trick, which itself may be immediately eclipsed by a version of the trick that the first reveal can't explain.
From Wikipedia (CC BY-SA 4.0).