The three main parts of the stage are upstage, downstage and center stage. Each part is defined by the distance from the audience and is used to aid actors in their movements on stage. Upstage refers to the part of the stage closest to the back wall. When upstage, actors are farthest from the audience. Actions taking place closest to the audience occur downstage. Center stage refers to the area between upstage and downstage, where the actor is at an equal distance from the proscenium and the back wall.
Each of the main parts of the stage is divided into left and right sections. The basis for the designation of the sides of the stage as left or right is determined by the perspective of the actor and not the audience. Like the division of the stage into upstage, downstage and center stage, this division is meant to help actors follow stage directions. Therefore, stage left refers to the part of the stage to the left of the actor, while stage right is the part of the stage to the actor's right.
Alternately referred to as the ante-proscenium because of its relative position to the proscenium, the front of house section is the part of the stage before the proscenium. This includes the section of the stage in front of the proscenium known as the apron.
The term "offstage" is used to refer to the parts of the stage that are invisible to the audience during performance. To the sides of the visible stage are the wings: the parts of the stage to the left and right that the audience cannot see through the framing of the proscenium. The area above the main stage is known as the scene house or fly loft.