The Proscenium Stage can be divided up into areas. Communication between performers, directors, designers, and technicians needs to be clear, so it is important for all students of theatre to use proper theatre vocabulary when describing where on stage an actor or object is.
The area closest to the audience is considered downstagewhile the area furthest away from the audience is considered upstage. Stage right and stage left (or, simply, right and left) are from the constant perspective of an actor standing on stage, facing the audience. Center (or center stage) is the area right in the middle of the stage, halfway between furthest upstage and downstage. Off or offstage is the area backstage, not included in the playing area. The playing area is considered on or onstage.
Two areas that serve as common reference points are the curtain line and the plaster line. The curtain line is the plane that the main drape or curtain travels down. This line divides the main stage area from the stage's apron. The plaster line is the imaginary line that travels downstage and upstage, dividing the stage in half.
Proscenium Stage Areas
Vocabulary: Upstage Downstage Center Right Left Onstage Offstage Curtain Line Plaster Line
Historical Perspective
The tradition of the upstage area being labeled "up" and the downstage area being labeled "down" has interesting beginnings. After the development of the Proscenium Arch stage, it was discovered that sightlines could be an issue when an audience sits on a level surface below the higher level surface of the stage. In order to remedy sightline issues, theatre designers build the stage on a rake, or slope. This helped the people closer to the front rows be able to see what was happening on the part of the stage further away from them. This also meant that to travel further from the audience was to, indeed, travel "up". To make a cross toward the audience was to, then, literally travel "down".
What staging issues do you suppose having a raked stage might have presented the performers and designers?