A major division in a drama. In Greek plays the sections of the drama signified by the appearance of the chorus were usually divided into five acts. This is the formula for most serious drama from the Greeks to the Romans and to Elizabethan playwrights like William Shakespeare. The five acts denote the structure of dramatic action. They are exposition, complication, climax, falling action, and catastrophe. The five act structure was followed until the nineteenth century when Henrik Ibsen combined some of the acts.
The Alchemist is a five act play. The exposition occurs in the first act when the audience learns of Subtle and Face's plan and meets the first of the victims. By the end of Act II, the complication, the audience has met the rest of the victims. The climax occurs in the third act when the victims all begin to arrive and Dapper must be gagged and locked in the privy. The near misses as each of the victims is targeted by the swindlers in a separate part of the house provides the falling action, and the catastrophe occurs in the last act when Lovewit arrives to restore order and each victim discovers the extent of the trickery.