Donald Trump has pleaded not guilty to 34 charges. Here's everything we know.

Donald Trump has pleaded not guilty to 34 felony counts of falsifying business records after an investigation into hush money paid to an adult film star.

Trump, the first sitting or former US president to face criminal charges, sat with his hands folded at the defence table as he entered his plea on Tuesday.

"Not guilty," the 76-year-old said.

Trump, who announced he is running for president in 2024, earlier held his fist in the air in a gesture to reporters as he departed his New York residence at Trump Tower in a motorcade bound for the courthouse.

From his motorcade, he posted on social media, "Heading to Lower Manhattan, the Courthouse. Seems so SURREAL - WOW, they are going to ARREST ME. Can't believe this is happening in America."

The charges come after Trump was indicted by a grand jury in New York last week. 

Trump surrendered to Manhattan District Attorney Alvin Bragg's office before the arraignment began in Justice Juan Merchan's court.

Here's everything we know so far.  

What do we know about the charges against Trump? 

Trump has been arrested and charged with 34 felony counts of falsifying business records.

In a statement, Bragg said Trump was accused of "falsifying New York business records in order to conceal damaging information and unlawful activity from American voters before and after the 2016 election," according to the ABC.

"During the election, Trump and others employed a 'catch and kill' scheme to identify, purchase, and bury negative information about him and boost his electoral prospects. Trump then went to great lengths to hide this conduct, causing dozens of false entries in business records to conceal criminal activity, including attempts to violate state and federal election laws," the statement said.

Taken together, the charges carry a maximum sentence of more than 100 years in prison under New York law but an actual prison sentence if he is convicted at a trial would almost certainly be far less than that.

While falsifying business records in New York on its own is a misdemeanour punishable by no more than one year in prison, it is elevated to a felony punishable by up to four years in prison when done to advance or conceal another crime.

So, why was Trump indicted in the first place? 

Before we get into that, let's cover what an indictment actually is. 

An indictment is different to a conviction.

According to the US Department of Justice, when a person is indicted, they are "given formal notice that it is believed that they committed a crime".

"The indictment contains the basic information that informs the person of the charges against them."

The Manhattan grand jury which indicted Trump last week heard evidence about a $US130,000 ($A192,614) payment made to adult film star Stormy Daniels, days before the 2016 presidential election, which Trump ended up winning. 

Daniels, whose real name is Stephanie Clifford, has said she was paid to keep silent about a sexual encounter she had with Trump at a Lake Tahoe hotel in 2006, the year after Trump married his current wife, Melania.

In 2018, Trump disputed knowing anything about the payment to Daniels. However, he later acknowledged reimbursing Cohen for the payment, which he called a "simple private transaction".

Trump's former personal lawyer Michael Cohen has said he coordinated with Trump on payments to Daniels and to a second woman, former Playboy model Karen McDougal. 

Trump has denied having had sexual relationships with either woman. 

In 2018, federal prosecutors examined the Daniels payoff, which lead to a prison sentence for Cohen but no charges against Trump.

Michael Cohen. Image: Spencer Platt/Getty.

What has Trump said?

In a statement last week, Trump called the indictment "political persecution and election interference".

"From the time I came down the golden escalator at Trump Tower, and even before I was sworn in as your President of the United States, the Radical Left Democrats – the enemy of the hard-working men and women of this country – have been engaged in a witch hunt to destroy the Make America Great Again movement," he said.

"The Democrats have lied, cheated and stolen in their obsession with trying to 'Get Trump', but now they've done the unthinkable – indicting a completely innocent person in an act of blatant Election Interference."

Trump went on to say he believes "this witch hunt will backfire massively on [current US President] Joe Biden".

"The American people realise exactly what the Radical Left Democrats are doing here. Everyone can see it. So our Movement, and our Party – united and strong – will first defeat [Democratic Manhattan District Attorney] Alvin Bragg, and then we will defeat Joe Biden, and we are going to throw every last one of these Crooked Democrats out of office so we can MAKE AMERICA GREAT AGAIN!"

TRUMP reacts in statement: “This is Political Persecution and Election Interference at the highest level in history”

— Maggie Haberman (@maggieNYT) March 30, 2023

What will this mean for Trump's 2024 presidential race?

In the US, there is nothing in the Constitution that prevents someone who has been charged or convicted from holding office. 

Trump also previously said he would continue campaigning for the Republican Party's nomination if he's charged with a crime.

Over the weekend, the 76-year-old released a new fundraising video for his presidential campaign. 

"We are officially a third world country. No president in the history of our country has been subjected to such vicious and disgusting attacks," he said in the video.

"But they only attack me because I fight for you... It's very simple. They can't buy me and they can't control me and that scares them beyond belief."

Former Arkansas governor Asa Hutchinson, who announced his candidacy for the 2024 Republican presidential nomination on Sunday, called on Trump to drop out of the race.

"I think it's a sad day for America that we have a former president that's indicted," Hutchinson said on ABC's This Week.

When asked whether Trump should step aside from the race, Hutchinson said, "Well, he should, but at the same time, we know he's not."

What other criminal inquiries is Trump facing?

Trump faces a separate criminal probe by a Democratic local prosecutor in Georgia into whether he unlawfully tried to overturn his 2020 election defeat in the state. 

He also faces two US Justice Department investigations led by a special counsel into efforts to overturn the 2020 election results and his handling of classified documents after leaving office.

Last month, Trump wrote on social media that he was expected to be arrested on March 21 and urged his supporters to protest to "take our nation back", reminiscent of his exhortations ahead of the January 6, 2021, attack on the US Capitol.

- With AAP.

This article was originally published on March 31, 2023, and was updated on April 5, 2023.

Feature Image: Shane Bevel/NCAA Photos/Getty.

 As one of our readers we want to hear from you! Complete this survey now to go in the running to win one of five $100 gift vouchers.