1) STRUCTURE (ACTS and SCENES)

Dramas are usually divided into 5 parts, called ACTS.

Modern dramas can have just 3, 2 or a single act.

Each act can be divided into several SCENES.

Since the Greek tragedies, based on Aristotle's Poetics, playwrights used to adhere to the three unities (unity of plot, unity of place and unity of time = there must be a single plot, taking place in the same environment and in one day). Shakespeare, like most of the playwrights in modern times never adhered to the three units.