On the frame stage, people imagine that there is a nonexistent "wall" at the entrance of the stage. It is produced by the association of "three-dimensional" spatial entities on the stage, and it is related to the "three walls" of the container set. Its function is to try to separate the actor from the audience, so that the actor can forget the existence of the audience and only admit the existence of the "fourth wall" in his imagination.

The concept of "the fourth wall" came into being in order to meet the requirements of drama to show the lives of ordinary people and truly show the living environment. During the Renaissance, it was suggested that if the indoor environment was displayed on the stage and the room lacked the fourth wall, it would not be true. There should be a fourth wall in front of the stage, which is transparent to the audience and opaque to the actors.

Classification of stage forms:

1, Frame Stage

A framed stage. It is also the most commonly used stage form for basic drama and stage. Like a picture frame, one side of the performance area faces the audience, and the audience sits on the side facing the stage to watch.

2. Stretching stage

Stretching stage. As the name implies, it means that a certain part of the stage extends outward and runs directly to the audience. The performance area faces the stage on three sides, and the audience can watch from the front, left and right directions. This kind of stage is widely used in concerts.

3. Annular period

The circular stage is usually located in the center of the venue, and the audience can watch it from all directions and interact with the performers personally.

4. Promotion stage

This kind of stage can create the effect of lifting and rotating, and with the performance content and stage lighting, create a sense of surprise and dream atmosphere.