Every story, whether read or performed, has a beginning. In performances following a story line, the beginning introduces the performers or characters and situates the story in terms of time and place. A good beginning also conveys the mood and a sense of the story's general atmosphere in a manner that is viewed or deduced rather than directly heard or read in dialogue. The beginning also provides the exposition or revelation of background information necessary for following the story as it unfolds.
Not necessarily acted out, the exposition is usually narrated or incorporated into the opening dialogue. The story begins with the "point of attack," the particular action that causes subsequent actions or from which the crisis will arise. The beginning is often the longest part, especially in operas and musical plays. Regular beginning features of such performances include opening choruses, preludes and overtures, and entrances for the main characters.
The middle part, or midpoint, presents a crisis or crises and the characters' part in either solving or escalating them. More complicated plots deal with several crises, one leading to the next. At this point, characters plot and scheme; pursue objectives and seek answers; or overcome obstacles and deal with intrigue. Constituting the main body of the performance, a good middle part creates a situation of mounting suspense and tension. Writers must integrate surface problems with harder-to-detect story problems that hold as the true underlying issue throughout the story.
The end part typically begins with the final confrontation of opposing characters or forces toward the resolution of the central crises or underlying story problem. At this point, objectives are archived, questions answered, and themes and suspicions confirmed. Endings do not have to resolve exactly as the audience expects; a realistic ending is generally a bittersweet ending. This third act of the story line also ties up loose ends and provides answers to questions raised in the beginning and middle parts, leaving the audience satisfied.
While the three-part structure of beginning, middle and end is the most common way of subdividing a performance, there are no strict rules for structuring a performance. Some contemporary operas and musicals employ a simpler, two-part structure. Other productions, depending on the complexity of the plot and length of the story, run from one to as many as seven acts.