Learning a part, including lines and movement, so they are able to take over a role for someone if needed when there is a planned or unexpected absence.
Running the backstage elements of the play and supervising the backstage crew. Organising the rehearsal schedule and keeping lists of props and other technical needs. Creating a prompt book and calling the cues for the performance.
Overseeing the creative aspects of the production. Developing a 'concept' or central idea for the production. Liaising with designers, rehearsing the actors and ensuring that all technical elements of the play are ready. Giving 'notes' to the actors to help improve their performances and agreeing the blocking of the actors.
Designing the sound required for the performance, which may include music and sound effects. Considering if amplification such as the use of microphones, is needed, and creating a sound plot.
Designing the set of the play and the set dressing (objects placed on the stage). Providing sketches and other design materials before overseeing the creation of the set.
Designing what the actors wear on stage. Making sure that costumes are appropriate for the style and period of the piece. Ensuring the costumes fit the actors.
Designing the lighting states and effects that will be used in a performance. Understanding the technical capabilities of the theatre and creating a lighting plot.