Stage Terms
                Imaginary lines from the audience to the stage. They can either be good or bad.
Sight lines
The invisible wall through which the audience watches the action of the play.
The fourth wall
The picture frame that frames the wall through which the audience watches the action of the play.
The proscenium arch
The part of the stage that holds the greatest focus.
What is Centerstage
To move upstage behind a person or prop. To move downstage in front of a person or prop.
What is cross above/cross below
To say something that is not specifically given in the script.
Ad-lib or Impromtu