Donald Trump was impeached by the House for a second time on 13 January on the charge of "incitement to insurrection" after his supporters breached the US Capitol during a joint session of Congress confirming the presidential election results.
The riot came on 6 January after a "Save America Rally" in the Ellipse, a park near the White House, in which Mr Trump spoke for more than an hour in an airing of grievances against the election, the media, the Democrats and more.
“President Trump gravely endangered the security of the United States and its institutions of Government,” reads the four-page impeachment article. “He will remain a threat to national security, democracy, and the Constitution if allowed to remain in office.”
This is what happens next.
The Senate impeachment trial began on 9 February and it is currently unclear how long it will last. However, it is expected to take less than the nearly three weeks that were used for Mr Trump's first impeachment trial in 2020.
Senate rules dictate that the chamber must be transformed into a court of impeachment almost immediately and remain that way until a verdict is reached.
Mr Trump will not be attending any of the sessions, and will be represented by lawyers David Schoen and Bruce Castor, who lead his legal team.
House members act as prosecutors during the trial, while senators sit as jurors, with Patrick Leahy, the president pro tempore of the US Senate, presiding over the proceedings.
Chief Justice John Roberts, who presided over Mr Trump's first impeachment, was originally supposed to serve in the same role for the second trial, but declined as he is not constitutionally obliged now that the former president has left office.
If senators vote that the trial is constitutional, then both the prosecutors and Mr Trump's defence will have 16 hours each to make their case.
Senators will then have four hours to question both sides, before each will have the same amount of time to argue whether motions to subpoena witnesses should be heard.
If they are issued, then both sides will depose witnesses, before they each have four hours to make their closing arguments.
Following that, the Senate will vote on the article of impeachment.
Read more: Can Trump run again in 2024?
In his first impeachment, the Senate largely voted along party lines to clear the president.
The Senate needs a two-thirds majority to achieve a conviction. With the chamber split at 50-50, even the vice president's tie-breaking vote will not be enough for Mr Trump to be impeached.
That means about 17 Republicans will need to join Democrats in turning on the GOP's former leader. In the House, 10 Republicans voted to impeach. And at least four Senators have indicated they are either undecided or leaning toward impeachment, including Mitch McConnell, Lisa Murkowski, Ben Sasse, and Pat Toomey.
Read more: What does impeachment mean for Trump?
Impeachment is a process encoded in the US Constitution for the specific purpose of removing a sitting president from office for "treason, bribery, or other high crimes and misdemeanours".
What, then, is the motivation for impeaching a civilian no longer sitting in the office of president? There are a few reasons, first among them preventing Mr Trump running for a second term in 2024.
While impeachment may not automatically bar him from running for office a second time, a second vote in the Senate to do so would only need a simple majority and not the two-thirds majority required for conviction, with the vice president currently holding the tie-breaking vote.
The impeachment could also precede a criminal investigation, with the Constitution saying a president convicted in the Senate is nevertheless "liable and subject to indictment, trial, judgment and punishment, according to law".
If it could be proven in a civilian court that Mr Trump broke the law, however, he wouldn't need to first be impeached before facing criminal charges.
Other outcomes include losing the former president's $1m travel allowance, lifelong pension, Secret Service detail, and the right to be buried with honours.
Read more: Which US presidents have been impeached?