Key Moments of the 2016 Election

— -- As this historic and wildly unpredictable election comes to a close on Election Day, it may be hard to remember how America got here.

It began with five candidates hoping to be the Democratic nominee -- Hillary Clinton, Bernie Sanders, Martin O’Malley, Lincoln Chafee and Jim Webb.

And on the other side of the aisle, a historic number of Republican candidates made a bid for their party’s nomination: Donald Trump, Ted Cruz, Marco Rubio, John Kasich, Jeb Bush, Ben Carson, Carly Fiorina, Rand Paul, Chris Christie, Scott Walker, Mike Huckabee, Bobby Jindal, Rick Perry, Rick Santorum, Lindsey Graham, Jim Gilmore and George Pataki.

After a grueling primary, it whittled down to two -- Clinton and Trump.

Here is a refresher of key moments Clinton and Trump faced in their pursuit of the presidency:

April 12, 2015 - Hillary Clinton Announces Run for President

After losing the 2008 election primary to President Obama and then serving as his secretary of state, Clinton decided to have another go at the presidency.

Clinton launched her second campaign with a video message posted to her new campaign website.

"Everyday Americans need a champion and I want to be that champion,” Clinton said in her presidential announcement video, adding, "So I’m hitting the road to earn your vote because it’s your time.”

June 16, 2015 - Donald Trump Announces Run for President

The real estate mogul and reality television star glided down an escalator to his presidential announcement where he told supporters gathered at Trump Tower in New York City he’s "officially running for president of the United States."

Donald Trump also declared if elected, he would “build a great wall” on the U.S.-Mexico border, “have Mexico pay for the wall,” and “be the greatest jobs president that God ever created.”

In setting the tone of his campaign, Trump said, “When Mexico sends its people, they’re not sending their best. They’re not sending you. They’re not sending you. They’re sending people that have lots of problems and they’re bringing those problems with us. They’re bringing drugs, they’re bringing crime, they’re rapists, and some, I assume, are good people.”

Aug. 6, 2015 - First Republican Primary Debate

The first Republican primary debate featured 10 candidates, the most on one debate stage in modern history, but Trump was the center of attention.

Trump, who had never been on a debate stage in his life, elicited boos from the audience for not ruling out running as a third party candidate and for not pledging his support to the eventual Republican nominee (if it were not him).

Trump was also asked by moderator Megyn Kelly about his treatment of women, a question that set the business mogul off against the Fox News anchor.

Sept. 8, 2015 - Clinton Apologizes for Private Email Server

In an interview with ABC News’ David Muir, Clinton apologized for her private email server she kept when she was secretary of state. The controversy over her private email server has continued to dog Clinton’s campaign. It also contributed to some voters’ concerns that Clinton is too secretive and untrustworthy.

“I should have used two accounts. One for personal, one for work-related emails,” Clinton said. “That was a mistake. I’m sorry about that. I take responsibility.”

Oct. 22, 2015 - Clinton’s Benghazi Hearing

Clinton testified before a House Select Committee regarding the Sept. 11, 2012, terrorist attack at the U.S. compound in Benghazi, Libya in which four Americans were killed including Ambassador Chris Stevens. The hearing lasted more than 11 hours.

Oct. 13, 2015 - First Democratic Primary Debate

Clinton was joined on stage at the Wynn Las Vegas by her four fellow contenders for the White House -- former Maryland Gov. Martin O’Malley, former Rhode Island Gov. Lincoln Chafee, former Virginia Sen. Jim Webb, and her toughest primary competitor Sen. Bernie Sanders.

Perhaps the most memorable moment from the debate was Bernie Sanders’ remarks on Clinton’s private email server.

“The American people are sick and tired of hearing about your damn emails,” Sanders said. “Let's talk about the real issues facing America.”

Dec. 7, 2015 - Trump Proposes a Ban on Muslim Entry to U.S.

In a statement released Monday Dec. 7, Trump called for a "total and complete shutdown" of Muslims entering the United States until "our country's representatives can figure out what is going on." Later that day, Trump read the statement to his crowd of supporters at a rally in Mount Pleasant, SC.

The statement was criticized by liberals and Trump’s fellow Republican candidates as Islamophobic and divisive.

Feb. 2, 2016 - Iowa Caucuses

In the first contest of the primaries, Clinton had an incredibly narrow win in the Democratic Iowa caucuses, beating Sanders by a mere three-tenths of a point.

“The results tonight are the closest in Iowa Democratic caucus history," the state's Democratic chairman Andy McGuire said in a statement that day.

For Trump, however, he came in second to Ted Cruz, finishing three points behind the Texas senator.

Feb. 9, 2016 - New Hampshire primaries

The New Hampshire primaries were momentous for Trump and Sanders -- both beating out the rest of their field with double digit leads. Out of the Republican candidates, Trump got his first win of the election with 35.3 percent of the vote. Sanders delivered a blow to Clinton’s campaign with a landslide finish in the Granite State. Sanders won 60.4 percent of the vote compared to Clinton’s 38 percent.

Sanders and Trump appealed to the white working class who sought to take on the “Washington establishment.”

May 3, 2016 - Ted Cruz Drops Out

The Republican primaries (and debates) were highly competitive, brutal, and at times, downright ugly. But no two Republican candidates had such an vicious rivalry as Cruz and Trump. At first cordial friends, Cruz and Trump were vaulting insults at each other nearly every day as the Republican primaries winded down. Trump called Cruz ‘Lyin’ Ted,’ and made personal attacks against Cruz’s family. Cruz hit back, calling the business mogul “pathological liar“ and a “narcissist.“

As Cruz picked up more states and delegates in the primaries, it seemed that the GOP was on the path to a contested convention. Yet, that all ended after Cruz lost the Indiana primary and mathematically eliminated from clinching the Republican nomination.

“From the beginning I said I would continue on, as long as there was a viable path,” Cruz said. “Tonight, I’m sorry to say, it appears that path has been foreclosed.”

May 26, 2016 - Trump Hits Magic Number to Clinch the Nomination

The battle for Republican primaries was hard fought, but Trump surpassed the 1,237 delegates need to secure the Republican nomination.

The billionaire-turned-politician celebrated the milestone in his campaign with McDonald’s and a Diet Coke aboard his private jet.

June 6, 2016 - Clinton Secures Enough Delegates to Clinton Nomination

Clinton obtained enough delegates to clinch the Democratic nomination, according to ABC News estimates based on superdelegate counts from the Associated Press that were announced late that Monday night.

Sen. Bernie Sanders’ campaign, however, called it a “rush to judgment” to “count the votes of superdelegates before they actually vote at the convention” and vowed to keep campaigning in the hopes that superdelegates would flip their allegiances to Sanders.

June 16, 2016 - Sanders Tells His Supporters He’ll Join Effort to Defeat Trump

This seemed to mark the beginning of the end for the Sanders campaign. In an online address to his supporters, Sanders said he would join Clinton in helping her defeat Trump, though he did not formally concede or endorse.

“The major political task that together we face in the next five months is to make certain that Donald Trump is defeated and defeated badly, and I personally intend to begin my role in that process in a very short period of time,” Sanders said.

Sanders campaign manager also confirmed to Bloomberg News that the campaign would no longer actively lobby super delegates to vote for Sanders.

July 5, 2016 - FBI Announces Its Not Recommending Criminal Charges Against Clinton

In the conclusion to a year-long investigation, FBI Director James Comey announced the FBI won’t be recommending criminal charges against Clinton for using a private email server.

“Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information,” Comey said.

Comey and the agency’s recommendations did not sit well with Trump and his supporters. Trump tweeted the “system is rigged.”

July 12, 2016 - Sanders Endorses Clinton for President

At a rally in New Hampshire, Sanders endorsed Clinton for president, vowing to do “everything I can to make certain” Clinton wins in November.

"I have come here to make it as clear as possible as to why I am endorsing Hillary Clinton and why she must become our next president," said Sanders, whose endorsement of Clinton upset a number of his devoted supporters.

"Secretary Clinton has won the Democratic nominating process, and I congratulate her for that," he added.

July 16, 2016 - Trump Officially Introduces Mike Pence as His Running Mate

Trump had a moment of pause in announcing his running mate, due to a deadly attack in Nice, France, and a growing frustration over leaks about his vice presidential pick.

But on July 16, two days after the news broke, from the Hilton Hotel Ballroom in New York City, Trump officially announced he had picked Indiana Gov. Mike Pence to be on the Republican ticket with him for “party unity.”

July 20, 2016 - Ted Cruz Tells RNC to ‘Vote Your Conscience’

Trump's former rival Sen. Ted Cruz was booed at the Republican National Convention for not endorsing Trump, and instead encouraging voters to “vote your conscience.”

"To those listening, please, don’t stay home in November,” Cruz said. “If you love our country, and love your children as much as I know you do, stand, and speak, and vote your conscience, vote for candidates up and down the ticket who you trust to defend our freedom and to be faithful to the Constitution.

July 21, 2016 - Trump Accepts Republican Nomination

Capping off four days of the Republican National Convention in Cleveland, Trump took the stage to accept the Republican nomination and deliver a 75-minute speech, the longest convention speech in modern history.

"I have loved my life in business. But now, my sole and exclusive mission is to go to work for our country -- to go to work for all of you," Trump said.

Trump also became the first Republican nominee to mention the LGBT community in an acceptance speech.

July 22, 2016 - Clinton Chooses Tim Kaine for Her Running Mate

Clinton announced in a text message to her supporters that she had chosen Virginia Sen. Tim Kaine as her running mate.

July 28, 2016 - Clinton Makes History Accepting Democratic Nomination

At the Democratic National Convention in Philadelphia, Clinton made history as the first woman presidential nominee for a major party.

"Today, we've reached a milestone in our nation's march toward a more perfect union: The first time that a major party has nominated a woman for President," Clinton said in her speech accepting her party’s nomination. "Standing here as my mother's daughter's, and my daughter's mother, I'm so happy this day has come."

Aug. 17, 2016 - Trump Shakes Up Campaign With New Manager and CEO

This was just one of several campaign shake-ups for Trump. After the firing of campaign manager Corey Lewandowski and the resignation of campaign chair Paul Manafort, Trump announced two new additions to the Trump team. Trump brought on pollster Kellyanne Conway as his new campaign manager and Breitbart chairman Steve Bannon as CEO to run his campaign.

Sept. 10, 2016 - ‘Basket of Deplorables’

Clinton made a gaffe that critics equated to former Republican nominee Mitt Romney’s “47 percent” comments made during the 2012 election.

"To just be grossly generalistic, you can put half of Trump supporters into what I call 'the basket of deplorables,' right? Racist, sexist, homophobic, xenophobic, Islamophobic, you name it. And, unfortunately, there are people like that and he has lifted them up,” Clinton said during a fundraiser in New York City.

Trump called on Clinton to apologize for her “insulting” comments.

Clinton only issued a statement that said, “Last night I was ‘grossly generalistic,’ and that's never a good idea. I regret saying ‘half’ -- that was wrong.”

Sept. 11, 2016 - Clinton ‘Overheats’ at 9/11 Memorial, Campaign Reveals Clinton Has Pneumonia

Video showed Clinton needing assistance getting into a van and as her knees buckling as she left a 9/11 memorial service.

Clinton personal doctor revealed later that day that Clinton left the event because she had “became overheated and dehydrated” and that Clinton was diagnosed with pneumonia on Friday, Sept. 9.

The incident occurred as Trump has been pushing the narrative that Clinton “lacks the mental and physical stamina.”

Sept. 26, 2016 - The First Presidential Debate

In one of the most highly anticipated events, Clinton and Trump faced off in their first presidential debate at Hofstra University in Long Island, NY.

Some 10 days before debate, Trump denied the false birther theory he peddled for years and stated that “President Barack Obama was born in the United States - period.”

When asked about it during the debate, Trump said, “I say nothing because I was able to get him to produce it. He should have produced a long time before….And I think I did a great job and a great service, not only for the country but even for the president in getting him to produce his birth certificate.”

Clinton also hit Trump for his past comments about Alicia Machado, the former Miss Universe winner.

Oct. 7, 2016 - WikiLeaks Release Thousands of Clinton Campaign Chair’s Emails

WikiLeaks published its first trove of hacked emails from Clinton’s campaign chairman John Podesta on Friday Oct. 7 and since then, several batches of Podesta emails have been released almost daily.

One email appeared to contain excerpts from Clinton’s private paid speeches. In these excerpts, Clinton said her “dream is a hemispheric common market, with open trade and open borders” and spoke of needing “both a public and private position.”

Other emails that would come out in later days included one in which Bill Clinton aide, Doug Band, detailed how he and his team “solicited and obtained” speaking deals for the former president and how Band persuaded clients of his consulting firm Teneo Strategies to donate to the Clinton Foundation.

Hillary Clinton's campaign has not confirmed or denied the authenticity of the emails. ABC News has not determined the authenticity of the emails published by WikiLeaks.

Oct. 7, 2016 - Trump Is Heard Making Lewd Comments About Women in 2005 Video

The Washington Post released video from 2005 of Trump bragging about his ability to grope women because he's "a star." Trump can be heard bragging to former "Access Hollywood" host Billy Bush about being able to do “anything” to women because he was famous.

Around midnight, Trump released an apology video to his Facebook, addressing the video.

"I never said that I'm a perfect person, nor pretended to be someone that I'm not," Trump said in the video. "Anyone who knows me knows these words don't reflect who I am. I said it, I was wrong and I apologize."

Oct. 9, 2016 - The Second Presidential Debate

The tension was palpable as the two candidates avoided shaking hands at the beginning of the town hall-style second presidential debate.

Trump was asked about the 2005 "Access Hollywood" video and whether if he did any of the things he described in the video, which included kissing women against their will and grabbing their genitalia. Trump said no and said it was “locker room talk.”

Trump also said he would appoint a special prosecutor to investigate Clinton’s emails.

Oct. 19, 2016 - The Final Presidential Debate

In the final presidential debate between Clinton and Trump, the Republican nominee would not commit to accepting the results of the election on Nov. 8 if he loses.

“I will look at it at the time. What I’ve seen, what I’ve seen is so bad,” Trump said, adding, “What I’m saying is that I will tell you at the time. I’ll keep you in suspense, OK?”

Trump had been arguing that the election is “rigged.”

Clinton slammed his debate comments as “horrifying.”

Trump also losing his cool, called Clinton a “nasty woman” when Clinton was answering a question on Social Security.

Oct. 28, 2016 - The FBI Reviews New Emails Tied to Clinton Private Email Server Investigation

FBI Director James Comey, in a letter to Congress, revealed that the FBI has learned of emails, discovered in an unrelated case, that "appear to be pertinent to the investigation" of Clinton's private email server, a case the FBI closed in July.

It was reported later that day that the newly discovered emails came from the separate federal investigation of former New York Rep. Anthony Weiner and his alleged sexually explicit messaging with an underage girl. The FBI is focusing on the emails his recently separated wife and Clinton insider, Huma Abedin sent from a laptop they shared.

The relevance of the emails has not been determined.

ABC News' Liz Kreutz, John Santucci, Candace Smith and MaryAlice Parks contributed to this report.