A Greek chorus is a group of performers in ancient Greek theater who comment on the action of a play. They often sing, dance, and recite lines together, providing background information, reflecting on themes, and expressing the collective emotions of the characters. The chorus helps to engage the audience and offers insights into the moral and social implications of the story. Typically, the Greek chorus consists of around 12 to 15 members, who represent the voice of the community or society. They often interact with the main characters, guiding the audience's understanding of the plot and enhancing the dramatic experience through their commentary and reactions.