• The memos contain unsubstantiated claims that Russian officials tried to obtain influence over Mr. Trump by preparing to blackmail him with sex tapes and bribe him with business deals. They also claim that the Trump campaign met with Russian operatives to discuss the Russians’ hacking and their leaking of emails and documents from the Democratic National Committee and from Hillary Clinton’s campaign chairman, John D. Podesta.
• The Washington firm and the former British spy, not identified here because of a confidential source agreement with The New York Times, gave the memos first to their clients but later to the F.B.I. and multiple journalists at The Times and elsewhere. The memos, totaling about 35 pages, also reached a number of members of Congress.
• Last week, when the F.B.I., C.I.A. and National Security Agency gave a classified report on the Russian hacking and leaking and efforts to influence the presidential election to Mr. Obama, Mr. Trump and congressional leaders, they attached a two-page summary of the unverified allegations in the memos.
What We Don’t Know
• Whether any of the claims in the memos are true. American intelligence agencies have not confirmed them, and Mr. Trump has said they are a complete fabrication. In addition, one specific allegation — that Mr. Trump’s lawyer, Michael Cohen, met with a Russian official in Prague in August or September — has been denied by both Mr. Cohen, who says he has never been to Prague, and the Russian, Oleg Solodukhin.
• Who concocted the information in the memos, if it is entirely false or partially so, and with what purpose. Did the British intelligence officer accurately report what he heard? Who gave him the information that, if false, amounts to a very sophisticated fabrication?
• What exactly prompted American intelligence officials to pass on a summary of the unvetted claims to Mr. Obama, Mr. Trump and Congress? Officials have said they felt the president-elect should be aware of the memos, which had circulated widely in Washington. But why put the summary in a report going to multiple people in Congress and the executive branch, virtually assuring it would be leaked?
• What will happen now. The F.B.I. has been investigating the claims in the memos, and Democrats are demanding a thorough inquiry into the reports that Trump representatives met with Russian officials during the campaign. But as of Jan. 20, Mr. Trump will be in charge of the bureau and the other intelligence agencies, and he may not approve such an investigation.
Questions You May Be Asking
• Everyone is talking about this document and passing it around online. Why can’t I read it on your website?
Because the 35 pages of memos prepared as opposition research on Mr. Trump contain detailed claims that neither the intelligence agencies nor The Times have been able to verify, the editors decided to briefly summarize the claims and not publish the document.
• Why did The Times and other outlets report extensively on the hacking of Democratic National Committee and Podesta emails before the election, but not this?
The Times did report before the election that the F.B.I. was investigating claims about Mr. Trump’s ties to Russia – an article that resulted from an extensive reporting effort. The D.N.C. and Podesta emails were public, their authenticity was not in doubt and they contained newsworthy information.
• Why did James B. Comey, the F.B.I. director, write two letters about Hillary Clinton’s emails before the election, but not about this?
That is a question Mr. Comey may eventually have to answer. His two public statements about the bureau’s investigation of the Clinton emails were highly unusual and a break with long F.B.I. tradition.
• There are reports that many people in the media knew about this opposition research on Mr. Trump and Russia for months, but it was never raised during the campaign. Why not?
Many reporters from multiple news organizations tried to verify the claims in the memos, but were unsuccessful. That does not mean none of the claims are true, but most news organizations choose not to publish damaging allegations against a public figure unless they believe them to be true.
• So what changed on Tuesday? Why is this now being reported and discussed by every media organization?
CNN broke the news that a summary of the memos had been attached to the classified report by the F. B. I, C.I.A. and National Security Agency on the Russian hacking and leaking during the presidential election and that it was given to Mr. Obama, Mr. Trump and Congressional leaders last week. That level of official attention prompted media organizations to decide to inform the public about the memos.
• The president and president-elect were given a two-page report, but there is a much longer document on BuzzFeed. What’s the difference?
BuzzFeed made the controversial decision to publish the opposition research memos in full, despite the fact that their reporters had not confirmed or disproved the claims in them. The two-page document is a summary of the claims in the series of memos.