Aristotle stated that six elements compose drama. They are plot, theme, character, dialogue, music and visual elements. All these elements except dialogue can be illustrated to the audience through theatrical nonverbal communication. The theater depends heavily on nonverbal communication to inform and move its audience. Acting, blocking, costume, lighting and set design can all help achieve that goal.
At the most individual level, nonverbal communication takes place through the actor onstage. Though her character may have dialogue, she communicates just as much with her physicalization and movement as her words. The way she carries herself, walks, sits and performs any physical activity tells the audience plenty about her character. For example, a nervous flighty character may move quickly, play with her hands or tap her toes while sitting and shrink back when confronted by another character. Nonverbal communication can even contradict the spoken dialogue to add complexity and tension to the character and her interaction with others.
The director's blocking, or placement of actors onstage, also acts as a significant form of nonverbal communication. Where characters stand onstage and how they move about can tell the audience much about their relationship with each other and their environment as well as a type of hierarchy of characters. For example, the protagonist is often placed in visually "powerful" or eye-attracting positions onstage. The audience sees the story through her eyes, so she must be the visual focus of much of the action so the audience can relate to her.
A costume is an immediate nonverbal sign to audiences about a character's class, age, personality and era. For example, in "A Streetcar Named Desire",Blanche wears a dingy, torn prom dress while reminiscing about her youthful days. Of course, Blanche's youth has faded, and she is desperately grasping on to something that no longer exists -- something that is as torn and mangled as she is. In this case, Blanche's costume gives the audience a piece of the story they cannot get from Blanche's spoken or nonverbal communication.
Lighting can indicate place, time, mood and focus of story to an audience. For example, a scene taking place under a full moon will have completely different lighting than the same scene happening at dawn or inside a kitchen. Lighting helps create the world the audience willfully enters when they watch a production. It can set mood through color and intensity and can "tell" the audience what to focus on onstage.
The set, like lighting, sets mood, environment and time. It tells the audience if the characters are in a hostile, friendly or neutral environment. At times, the set can be so simple, place and time are implied, which of course, is also nonverbal communication. A set's absence can communicate a desolate or unfinished world for the characters, or it can serve as a technique to "break the fourth wall" between actors and audience, allowing the audience to be more consciously aware of the fact that they are watching a make-believe world.