US President Donald Trump and Democratic challenger Joe Biden will go head-to-head in three debates prior to the US election.
There is also one debate scheduled for their vice-presidential candidates, Mike Pence and Kamala Harris.
They are seen as being among the top political events to watch during the US election season.
The moderators for the four debates, which typically draw large TV audiences, have now been announced.
When are the Trump v Biden debates – and who are the moderators?
Fox News Sunday anchor Chris Wallace will host the first presidential debate on 29 September, in Cleveland.
Miami will be the host city for the second, a town-hall style debate on 15 October, moderated by C-SPAN’s Steve Scully.
NBC’s Kristen Welker will host the final presidential debate on 22 October in Nashville.
The sole vice-presidential debate, between Democrat Kamala Harris and Republican Mike Pence, will be in Salt Lake City, Utah on 7 October.
That event will be moderated by USA Today Washington Bureau chief Susan Page.
All of the debates are scheduled to take place from 21:00-22:30ET (02:00-03:30GMT) with no commercial interruptions.
The US election will be held on 3 November.
How important are the debates?
Debate viewership in terms of audience share has dropped in recent years, according to the Pew Research Center, but millions of voters still regularly tune in.
The first debate between Mr Trump and former Democratic presidential candidate Hillary Clinton was a major draw in 2016, with a reported record 84 million viewers, according to data from Nielsen Media Research. Pew Research polling also indicates that voters find the debate performances are a factor in helping them choose their preferred candidate.
Who is Chris Wallace?
The first debate will be divided into six segments of approximately 15 minutes each, the nonpartisan Commission on Presidential Debates (CPD) announced.
The topics will be selected by Wallace, a longtime Fox News anchor known for his memorable TV interviews with Mr Trump, and will be announced one week before the debate.
Each segment will open with a question and the candidates will get two minutes each to respond, the CPD said.
Wallace, a registered Democrat, hosted the final 2016 debate between Mr Trump and Hillary Clinton and won widespread praise from commentators at the time for pressing each candidate on uncomfortable issues.
Mrs Clinton was asked about her use of a private email server as secretary of state and sexual assault and misconduct allegations against her husband, while Mr Trump was questioned on allegations of sexual assault against him and his stated unwillingness to accept the results of the election.
His performance was praised on both sides of the political spectrum for his even-handed approach and for not letting either candidate digress too wildly.
“I take it very seriously,” Wallace said on his programme as he prepared for the debate. “This is not a TV show. This is part of civics, the constitution, if you will, in action, because this is helping millions of people decide who we’re going to elect as the next president.”
Wallace has occasionally clashed with Mr Trump during his presidency, including in an interview with him last month in which he questioned him about a cognitive ability test Mr Trump touted.
“It’s not the hardest test,” Wallace said after revealing that he had also taken it. “They have a picture and it says ‘what’s that’ and it’s an elephant.”
In April, Mr Trump lashed out a Wallace, tweeting: “Just watched Mike Wallace wannabe, Chris Wallace, on @FoxNews”, in a reference to Wallace’s father, one of the original members of CBS 60 Minutes.
Mr Trump also called him “even worse” than the presenters of NBC and CBS Sunday morning programmes, networks that Mr Trump is highly critical of and constantly refers too as “fake news”.
How did the Trump campaign respond?
The final list of moderators did not include any of those requested last month by Trump campaign aide and personal Trump lawyer Rudy Giuliani.
Trump campaign spokesman Tim Murtaugh said in a statement that “these are not the moderators we would have recommended” and alleged that “some can be identified as clear opponents of President Trump, meaning Joe Biden will actually have a teammate on stage most of the time”.
He added: “One thing is sure: Chris Wallace’s selection ensures that Biden will finally see him face-to-face after dodging his interview requests. That is, if Biden actually shows up.”
Before the moderators were announced, Mr Trump demanded that Joe Biden and he both be drug tested before the debates. He claimed this was due to a sudden improvement in Mr Biden’s performance during the Democratic primary debates. He also challenged Mrs Clinton to a pre-debate drug test in 2016.
What are the rules of the other debates?
The next debate to take place is the vice-presidential debate between Vice-President Mike Pence and California Senator Kamala Harris.
That debate will be divided into nine segments of about 10 minutes each. Like in the first debate, each section will begin with a question, with a candidate allowed two minutes to respond followed by debate.
The second presidential debate will take the form of a town meeting, and Floridians in the audience will pose questions of the candidates, who will be allowed two minutes to answer. The moderator will be allowed an addition minute to facilitate more debate. The questioners will be uncommitted voters selected by the chief scientist of Gallup.
The third debate will have identical rules to the first.