The fundamental action or conflict of a play is the plot. The plot is the backbone of any story, and it determines the structure, events, and themes of the play. It refers to the main events and their causal relationships that advance the story and drive the characters towards the resolution of the central conflict. The plot of a play typically involves various elements such as exposition, rising action, climax, falling action, and resolution or denouement. Each of these elements contribute to the play's progression and provide context for the characters' choices, obstacles, and outcomes.