A town-hall style debate, as the one scheduled for Sunday night, can be extremely dramatic, as candidates circle and stalk each other, walking around as if in a boxing ring, or have it out in an old-fashioned staring match.
Hillary Clinton, the more experienced of the two, knows how to use the stage, when to walk up to the audience, the questioner, and when to stay in the seat. She did that well at the Commander-in-chief town hall some weeks ago in New York.
Donald Trump, on the other hand, had seemed content to stay in his seat to answers questions from the moderator, NBC’s Matt Lauer, or a member of the audience. He did not use the rest of stage at all, but that could change for the real thing.
In a town-hall style debate, candidates sit on bar-type stools, with no podiums in front. The moderators — ABC’a Martha Raddatz and CNN’s Anderson Cooper, in this instance — will be seated behind tables instead.
It tends to be less formal than the stand-up, chained to the podium format of the first debate and is both conversational and confrontational, leading to heated back-and-forth between the candidates, without interruptions from the moderators.
In 2012, President Barack Obama and his Republican challenger Mitt Romney scored the most memorable moment of their debates at a town hall. Romney started it by trying to corner Obama on when he called Benghazi a terrorist attack.
The killing of US ambassador to Libya Chris Stevens and three other Americans in an attack on the country’s mission in Benghazi had turned into an election issue with Republicans accusing the administration of hesitating to call it a terrorist strike.
“You said in the Rose Garden the day after the (Benghazi, Libya) attack was an act of terror?” Romney challenged Obama, striding up to him confrontationally. Obama stared back, and replied, icily, “Please proceed, governor”.
Romney turned to the moderator, CNN’s Candy Crowley, and asked for the president’s answer to be recorded. He thought he had caught Obama in a lie. But Crowley sided with the president, saying, “He did, in fact, sir”.
Republicans later called Crowley unfair, and memories of it still fresh four years after, Trump, who is known to take liberties with facts, has told moderators, in the run up to his first debate against Clinton, to not fact-check him like Crowley.
It was town-hall style debate once again that gave the 1992 presidential race its iconic moment, when George HW Bush, the sitting president, was caught looking at his wristwatch as a member of the audience asked him a question.
As president, he was seen as signalling, he had more important things to do than waste his time with his challengers — Democrat Bill Clinton and Independent Ross Perot — or, in a sign of the highest act of political felony, with the audience.
Bush lost the election, and no candidate has ever looked at his or her watch since.
In 2000, as George W Bush, the Republican governor from Texas, was on his feet answering a question at a town hall when Al Gore, the Democratic vice-president, rose and walked menacingly towards him, as if to intimidate him.
Bush paused, looked at Gore, gave him a curt nod, and went back to his answer as the audience broke into laughter. Caught and foiled, Gore smiled and tried a comeback so pedestrian it never made it to history, as recorded by YouTube.