Donald Trump

There was a moment in the first US presidential debate when lots of people asked themselves: "Did Trump just say 'bigly'?"

Followed quickly by: "Is that even a word?"

It came during a discussion on fiscal policy, when, Donald Trump told his opponent: "I'm going to cut taxes bigly, and you're going to raise taxes bigly." Or so many thought, anyway.

Jimmy Carter and Ronald Reagan's debate in 1980 drew 80.6 million viewers.The viewing figures only count those who watched the debate on the 13 US TV channels that carried it live, meaning the true figure may be much higher.

Millions are also thought to have watched worldwide through online live streams or in bars and at parties.

But Trump never openly insulted Clinton, never called her "Crooked Hillary", nor did he cross the stage at any point, as a former senate opponent famously did with Clinton in 2000 - a move that was seen as physically intimidating towards a female candidate.

Despite that, gender and sexism did feature prominently during several exchanges in the debate, and in the initial feedback on the candidates' performance on social media.

1. Interruptions

Now, 20 years later, she is back in the headlines.

Ms Machado claims she was called "Miss Piggy" by Donald Trump, the Republican candidate for the White House who owned the beauty pageant when she won it.

The remarks were made, the Venezuela-born model says, after she put on some weight following her win.

How did it come up?

The issue was brought up by Hillary Clinton, the Democratic presidential nominee, during Monday's televised debate with Mr Trump. She was making a point about her rival's remarks about women.

Mr Trump said he held back "because he didn't want to hurt anyone's feelings".

In a Fox News interview, he also accused moderator Lester Holt of being tougher on him than on Mrs Clinton.

Overnight polls with small samples were split on who won, but more rigorous surveys are due in the coming days.

Initial estimates from research firm Nielsen suggest more than 80 million Americans watched the debate at home, but that figure will rise significantly when other forms of viewing are counted.

That drubbing is similar to Mitt Romney's dominant performance over President Barack Obama in the first 2012 presidential debate.

Voters who watched said Clinton expressed her views more clearly than Trump and had a better understanding of the issues by a margin of more than 2-to-1. Clinton also was seen as having done a better job addressing concerns voters might have about her potential presidency by a 57% to 35% margin, and as the stronger leader by a 56% to 39% margin.

Perhaps we should call it "Smackdown at the Mack," since it is being held at the Hofstra University's David S. Mack Sports and Exhibition Complex on New York's Long Island.

So how should you watch this D-Day of Debates? We have some tips for you:

What time does it start?

Republican Donald Trump and Democrat Hillary Clinton will take to the stage in New York on Monday night.

The duel at Hofstra University could be the most watched debate in television history, with 100 million viewers.

There are 43 days until the election, with one poll on Monday suggesting some movement towards Mr Trump.

When Hillary Clinton takes the stage at the first presidential debate, she will make history. Over the past few months the level of scrutiny faced by the first female candidate for president of the United States has ramped up: her policies, her emails, her relationships have been critiqued, dissected and analysed. And so have her clothes.

So who is the man asking the questions - and what does he have in store?

High profile

Lester Holt's CV includes major network shows such as Dateline NBC, Today, and his current role as anchor of NBC Nightly News, which attracts millions of viewers every night.

That makes him a national celebrity, and well used to high-stakes TV.

He has already been accused of political bias, when Mr Trump labelled him a Democrat and complained about the "unfair system".