Final answer:
An actor walking away from the audience on a stage is moving upstage. The term 'upstage' comes from the traditional raked stages, and it signifies the part of the stage farthest from the audience, whereas 'downstage' is closest to the audience.
Step-by-step explanation:
If an actor is near the edge of the stage closest to the audience, and she turns her back and walks away from the audience, she is walking upstage. The term upstage refers to the area of the stage that is furthest from the audience. This stems from the historical construction of stages which were raked (slightly sloped) with the higher end away from the audience. Conversely, the area closest to the audience is referred to as downstage.
In a traditional proscenium theatre, which is a common type of theater, the stage faces the audience directly and allows for clear demarcation of stage directions. When an actor moves downstage, they are moving closer to the audience, potentially creating a more intimate connection or addressing the audience more directly. Stage directions such as upstage and downstage are critical for actors to understand as they assist in ensuring clear and intentional movements within a performance.