In a play, stage directions are instructions from the playwright to the actors and stage crew. Though usually placed in brackets within scripts, they are not spoken. Stage directions relate the author's intentions for actors' entrances, exits, movement, intonation and essential behaviors. In addition, they provide guidance for the crew regarding their responsibilities, including what the lighting should be and any sounds, such as music, that must be added.
Stage directions sometimes provide information about what is happening on stage in the background, away from the main action. They also indicate the mood and environment envisioned by the playwright.
Stage directions often tell actors how they should speak, and these are indicated at the beginning of lines. For example, if a playwright wants an character to be furious, the script reads, "(angrily) Why are you leaving me?" Directions that are specifically intended for the stage crew, such as "(the door slams)," are typically separated from dialogue and placed on their own lines.
An important aspect of stage directions tells the actors their locations on stage. For example, "downstage" is near the audience and "upstage" is at the back, while "center stage" is between the two. In addition, "left" and "right" are indicated in reference to the actors' positions when facing the audience. For instance, when actors walk "stage right," they are moving to the audience's left side.