The formats for the three presidential and one vice-presidential general-election debates have been announced.

The debates will be 90 minutes, from 9 to 10:30 p.m. Eastern Time, without commercial breaks, according to the Commission on Presidential Debates, the nonpartisan, nonprofit group that sponsors the events.

They will be moderated by one person, who will guide the conversation so that "thoughtful and substantive exchanges" occur, the CPD said. As such, the moderator will have the discretion of extending segments and ensuring that candidates have equal time to speak.

The moderator alone will select the questions, which will not be known to the candidates or CPD.

The CPD is working with tech and civic groups who will help the moderators identify the most impactful topics of discussion.

The debates, in chronological order, as provided by the CPD:

First presidential debate

September 26, 2016

Hofstra University, Hempstead, N.Y.

HOST: Lester Holt, NBC Nightly News

The debate will be divided into six time segments of about 15 minutes each on major topics to be selected by the moderator and announced at least one week before the debate. The moderator will open each segment with a question, after which each candidate will have two minutes to respond. Candidates will then have an opportunity to respond to each other. The moderator will use the balance of the time in the segment for a deeper discussion of the topic.

Vice presidential debate

October 4, 2016

Longwood University, Farmville, Va.

HOST: Elaine Quijano, CBS News

The debate will be divided into nine time segments of approximately 10 minutes each. The moderator will ask an opening question, after which each candidate will have two minutes to respond. The moderator will use the balance of the time in the segment for a deeper discussion of the topic.

Second presidential debate

October 9, 2016

Washington University in St. Louis

HOSTS:

Anderson Cooper, CNN

Martha Raddatz, ABC

The second presidential debate will take the form of a town meeting, in which half of the questions will be posed directly by citizen participants and the other half will be posed by the moderator based on topics of broad public interest as reflected in social media and other sources. The candidates will have two minutes to respond, and there will be an additional minute for the moderator to facilitate further discussion. The town meeting participants will be uncommitted voters selected by the Gallup Organization.

Third presidential debate

October 19, 2016

University of Nevada-Las Vegas

HOST: Chris Wallace, Fox News

The format for the debate will be the same as the first presidential debate.

The format for this year's debates is based on the CPD's 2012 debate formats, which introduced longer segments, the group said.

“The CPD has a simple mission, to ensure that presidential debates help the public learn about the positions of the leading candidates for president and vice president,” CPD Co-Chairs Frank J. Fahrenkopf, Jr. and Michael D. McCurry said.

Steve Scully, C-SPAN's senior executive producer, White House and political editor, will serve as backup moderator for all the debates.