(Image Credit: Saul Loeb/AFP/Getty Images)

President Obama and Republican challenger Mitt Romney will face off tonight in the first presidential debate of the 2012 election. The forum will focus exclusively on domestic policy. Half of the debate will be on the economy, the other half will ask the candidates to address health care, their view of the role of government and their vision for governing.

Tune in to ABCNews.com today for live-streaming coverage of the first 2012 Presidential Debate from Denver. Coverage kicks off with ABC News' live preview show at noon, and full debate coverage begins at 8 p.m. Watch all the coverage HERE.

Here's what you need to know about tonight's big campaign moment.

When: 9:00-10:30 p.m. ET

Who: The first debate will feature the two candidates for president: President Obama and former Massachusetts Gov. Mitt Romney. (Vice presidential candidates will face off Oct. 11 in a debate moderated by ABC News' Martha Raddatz).

PBS NewsHour's Jim Lehrer will be the moderator tonight, his 12th time moderating a presidential debate. He also moderated the first presidential debate in 2008, in Oxford, Miss., between then-Sen. Barack Obama and Sen. John McCain.

Obama will sit to the right of Lehrer and Romney will sit to the left.

Where: The Magness Arena at the Daniel L. Ritchie Center for Sports and Wellness at the University of Denver.

Introductions:

Obama won the coin toss and will be introduced first, followed by Romney.

Opening Statements:

Neither candidate will have a chance to address the audience directly with an opening statement.

Format:

There will be six, 15-minute segments focused exclusively on domestic policy. Unlike the primary debates, there will be no applause allowed from the audience.

Segments 1, 2 and 3: The Economy

Segment 4: Health Care

Segment 5: The Role of Government

Segment 6: Governing

Lehrer will ask a question to open discussion in each segment and Obama and Romney will each have two minutes to respond.

The remaining time, approximately 10 minutes, will be devoted to further discussion moderated by Lehrer.

Closing Arguments:

Obama and Romney will have two minutes each to deliver their closing statements directly to voters at the end of the debate.

Romney won the coin toss and will make his statement last.

Next Up:

Obama and Romney will meet two more times on the debate floor: Oct. 16 and again Oct. 22 .