Answer:
The witches in Shakespeare's "Macbeth" create tension by making predictions about the future, which keeps the audience interested. Besides, they represent the supernatural world, since people in those times believed in curses and witches. Thus, they have the power to appear and disappear, as well as to look real, although they are not. Finally, they speculate with the Macbeth and the audience's dismay, as they are as dark, fearful and horrible as the protagonist's soul.