Complication is usually middle part of the plot (after exposition and before Denouncement). During complication protagonist finds troubles. The complication may be in form of twists in the plot, some new information/discovery, arrival of a new character or idea, and the conflict/opposition faced by protagonist.
The Denouement is the final moment in which all conflicts/crisis are resolved.
Crisis is the decisive moment of the play in which the conflict is about to be resolved. Here the rising action (complication) is about to reverse and become falling action.
Exposition is the start of play in which main characters are introduced with a glimpse to some of the conflicts of the play.
