4) CONVENTIONS

The proposition or prologue - it is present at the beginning of the play; its functions is to explain the action, the relationship between the characters and everything the audience needs to know.

In some plays (for examples in Shakespeare's) the prologue is recited by the chorus (that sometimes also comments on the characters and their action).

Through retrospection characters may remember significant past events.

In modern theatre, flashbacks often replace narration and are used to relate an incident that happened earlier.