Donald Trump is the first former US president to face criminal charges

New York prosecutors have been investigating the payment of hush money to an adult film star prior to his election in 2016.

Former porn star Stormy Daniels claims she had an adulterous affair with the former president, and was paid $130,000 to keep quiet

The payment was legal - but Trump allegedly recorded it as a business expense.

Falsifying business records is illegal in New York,

Trump is expected to appear in court to face the charges and enter a plea in New York next Tuesday.

He denies wrongdoing, and the affair, saying the indictment is "political persecution" US media say Trump faces more than two dozen charges linked to business fraud - although that is not officially confirmed Republicans are calling the indictment an "outrage", while Democrats say no-one is above the law

What is a grand jury?

Trump has been indicted following a decision by a grand jury, a part of the US legal system that may need some explaining to those outside the country and unfamiliar with the process.

A grand jury is a group of citizens that hear evidence from a prosecutor ahead of a trial.

Witnesses may be called to testify in front of them and evidence is shown.

The grand jury listens and then votes in secret about whether they believe there is enough evidence to charge the person with a crime.

A separate criminal trial with another jury awaits the indicted