How does one prevail in a battle of wits with a counter-puncher as mercurial as Donald Trump? Todd Harris, who was senior adviser to Senator Marco Rubio during the Republican primary debates, told the BBC’s Katty Kay: "Our strategy for most of the campaign was to ignore all of Trump’s taunts and insults, but the challenge with that was that the media wasn’t ignoring any of them."

In the run-up to the first debate, let's take a look at the latest Clinton and Trump campaign videos.

Clinton goes on the attack in Mirrors, external, targeting previous statements the Republican has said about women. The theme follows up on her advert Role Models, external over the summer, which shows scenes of young children watching some of Trump's most shocking statements.

There are no ads listed on Trump's campaign website, external, but the Team Trump YouTube channel's latest addition, Movement, external, boasts that their candidate is a "builder, business man, success".

With up to 100 million viewers expected tonight, a figure which would rival the Super Bowl, social media users have been passing around comparisons to the American football final. 

The BBC spoke to parents in Brooklyn about what they want to hear in tonight's debate.

Listen to the full programme here.

We may not know what will happen in this debate, but there are some things we can at least guess will come up: specifically, the words the candidates will use.

So feel free to use our bingo card: cross off each term when you hear it, and see how quickly you're able to complete a line of three in any direction.

Good luck...

Students at Hofstra University prepare to host the first presidential debate. 

Image source, Getty Images

Image source, Getty Images

Image source, Getty Images

Image source, Get

Image source, Getty Images

Image source, Getty Images

Image source, Getty Images

Trump has turned to Snapchat in his quest to court young voters ahead of the first presidential debate. 

The Republican nominee launched a nationwide Snapchat filter that features fireworks along with the words: "Debate Day: Donald J Trump vs. Crooked Hillary". 

A banner at the bottom also includes his campaign slogan, "Make American Great Again". 

Clinton used anti-Trump Snapchat filters at a Trump rally in California earlier this year and during July's Republican National Convention.

Commentators say Trump must avoid coming across as too aggressive tonight. Rick Lazio (pictured), who was Clinton's Republican opponent in the 2000 New York Senate race, was widely criticised when he walked over to her lectern during a debate and chastised her on political funding. The moment bears re-watching, external.

Image source, AP

Three subjects selected by moderator Lester Holt have already been announced: 

America's Direction

Achieving Prosperity 

Securing America

Another three questions will be pulled from news events.

Mr Trump and Mrs Clinton will each be given two minutes to respond to the moderator's question, and then they will be able to respond to each other.

There are no breaks during the 90-minute event.

Read more about Lester Holt

Green party candidate Jill Stein was ejected from campus hours before the debate was set to begin. 

She said on Twitter she was appearing on campus for a pre-arranged interview with MSNBC and was "immediately escorted" from campus and "told not to do any more press". 

Ms Stein and Libertarian Party Candidate Gary Johnson were not officially invited to the debate after failing to poll at least 15%, according to the Commission on Presidential Debates.

She then joined a rally outside the campus gates. 

Since Donald Trump announced his candidacy for the Republican party, the BBC has been interviewing his supporters to get a sense of what his appeal is.

The reasons are diverse, from the fact he does not have a political background...

...to his promises to rejuvenate the US economy, and to the fact he has a long history as a businessman.

You can read much more, and see more interviews in our article here.

We told you earlier that a Bloomberg poll on Monday gives Donald Trump a narrow lead against Hillary Clinton when the third-party candidates are taken into account.

Between now and the election, we here at the BBC are running a 'poll of polls', that looks at the five most recent national polls and takes the median value

This is how it looks right now, with Mrs Clinton in a 1% lead. If you want to look at the individual polls, and how they have changed over the past few months, you can click here.

It may be worth checking in later this week to see how the first debate has affected polls (hint: expect them to change).

You may well wonder why only Mr Trump and Mrs Clinton are invited to the debates, and why we are not seeing Libertarian candidate Gary Johnson and the Green Party's Jill Stein.

The fact is, under rules set by the independent Commission on Presidential Debates, external, candidates need to be polling at 15% or higher to be able to take part in a debate - as it stands, neither is near that benchmark, so won't be at Hoefstra University.

At one point earlier this summer, Harambe, the gorilla killed in Cincinnati Zoo in May, was polling at 5%, external.

Image source, Cincinatti Zoo

There are no reliable polls for where Harambe stands now, but it is unlikely he would have been invited to the debates, for a number of reasons:

• he is a gorilla
• he is dead
• he wouldn't have polled anywhere near 15%
• public safety

Harambe's absence was also noted by independent candidate Evan McMullin a few days ago.

Image source, Hillary For America

You may have seen this image a lot over the past few days: the viral photo of crowds of young women who turned their backs on Hillary Clinton to take a selfie.

It's now been explained by the photographer who took the shot.

Many internet users criticised the millennial generation for turning their back on the Democratic presidential candidate on Sunday, but as it turns out, it was Mrs Clinton's idea.

Barbara Kinney, a campaign photographer for Hillary Clinton and a former White House photographer to Bill Clinton, explained that Mrs Clinton had instructed the crowd to take selfies.

Mrs Clinton stood at the podium and said, external "Okay everybody, turn around and we’ll do a group selfie," she said, while asking her staffers to move out of the shot.  

Courtesy of our North America editor, who's at the debate venue in Hofstra University, New York.

Debates are a chance for the public to put candidates under the microscope, with everyone watching carefully for mistakes and defining moments.

Our man in New York, Nick Bryant, takes a look through past American presidential debates and discovers the turning points you might have forgotten.