what is the significance of the title 'Twelve angry men'?

The title is significant because the play is as much about the jurors as the defendant. We see these 12 men with their biases, individual experiences, economic differences, in addition to the conflicts they feel in regard to class, and are far better able to understand the jury system and its need for deliberation. In the play, we see each of these twelve men at their worst (well, juror number eight stands strong throughout), and we see how their opinions and misconceptions have been molded by their own experiences. We also come to see how these experiences can color their preconceptions of the defendant.