Five act structure
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The five act structure is that most used for novels and longer plays, though some more complex films use it. The concept comes from theatre, but the actual division into acts is not required, and it may have reached its greatest development among novelists.
[edit] The Structure
Act I, as in the three-act structure, is what one thinks of a The Beginning.
Act II may be considered part of the beginning or part of The Middle. Like so much in writing, this is a matter of consensus rather than laws promulgated by authority.
Acts III and IV are definitely The Middle, while Act V contains the material considered The End.
In Act I, the protagonist is introduced with a problem. In film, more background can be quickly shown as part of the set-up. (see Viewing vs. Reading) In theatre, there is always the danger of falling into The Dreadful Scene where two characters sit and talk between themselves strictly to give the audience background. In contemporary fiction, one should start as much in media res as possible and weave in background as necessary.
Act II introduces further complications as the protagonist finds out further ramifications of the problem. As a general rule in fiction, anything important to the climax or resolution of the final problem should be introduced by this point, if only mentioned in passing. This is foreshadowing: a late introduction makes it seem pasted on or "pulled out of a hat."
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