US intelligence agencies believe Russia tried to sway the election in favour of Mr Trump. A special counsel has been looking into whether anyone from his campaign colluded in the effort.
All we have is a summary of the conclusions, from the US attorney general. In a four-page letter to Congress, he said the special counsel found no evidence the campaign conspired with Russia.
No, Attorney General Bill Barr also said there was insufficient evidence that the president obstructed justice.
Yes. He had called it a witch hunt from the start.
No. It was conducted by the hugely respected Robert Mueller, a Republican who used to run the FBI.
There were several meetings between senior members of Mr Trump's team with Russian officials. Several meetings were not initially disclosed.
Ex-National Security Adviser Michael Flynn lied to the FBI about meeting the Russian ambassador to the US before Mr Trump took office.
The president's son, Donald Jr, met a Russian lawyer who said she had "dirt" on Hillary Clinton during the campaign.
He brought charges against several of Mr Trump's inner circle.
Ex-adviser Roger Stone has been charged with lying to Congress about his contacts with Wikileaks, which released emails belonging to Democratic officials, allegedly hacked by Russians.
Mr Trump's former lawyer Michael Cohen said Mr Trump knew in advance about the email dump. Mr Cohen admitted lying to Congress, campaign finance violations and tax evasion and received a 36-month prison sentence.
Former campaign chairman Paul Manafort lied to the FBI about his work in Ukraine, according to special counsel Robert Mueller, with whom he had been co-operating. Manafort has been jailed for bank fraud.
Since he fired the man leading one of the investigations, ex-FBI Director James Comey, there were questions about whether he obstructed justice.