How we change what others think, feel, believe and do
In the 'aside', the actor speaks directly to the audience or camera, effectively stepping out of the plot for a moment.
The aside is usually used to inform the audience of detail that might not be clear from the action. It also allows the actor to explain what they are thinking.
Shakespeare uses occasional 'asides' to help the audience (who were often common folk of the day) understand the intricacies of his plots.
Groucho Marx of The Marx Brothers used regular asides for great comic effect.
In this changed role, the actor typically takes on the mantle of the narrator, in which an explanatory commentary may be given.
In a written story, narration is woven amongst the active text. In a visual production this is not normally possible as live action is being presented.
Sometimes a particular single character takes on the role of occasional narrator. This is usually an endearing position where they take the part of the friend of the audience.
Asides can be used for comedy and not just narration. Thus the actor makes a witty aside that does little for the plot but does amuse the audience. For example, they might say 'Watch this!', effectively foreshadowing comic action to come.
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