Here is a rundown of what we know (and what we don't) so far:
What emails were discovered?
Many things remain vague and unknown about the newly uncovered emails. What we do know is that the FBI believes they are "pertinent" to its investigation into Clinton's use of a private server during her tenure as secretary of State. According to an official close to the investigation, there are thousands of new emails under review. What we don't know is whether they contain any classified material or could have any bearing on the previous investigation.
Could the emails lead to criminal charges against Clinton?
That is impossible to know at this point. In a speech Friday, Clinton said she is "confident" that the new developments won't change the FBI's recommendation not to prosecute her for improperly handling classified materials. Although Comey could not put a timetable on how long it will take to review the new material, a source tells USA TODAY that is unlikely it will be completed before Election Day.
Why did Comey make the review public?
In his letter to lawmakers, informing them of the latest developments, Comey said he thought it was important to update them "in light of my previous testimony," which said the investigation had been concluded.
Did Attorney General Loretta Lynch approve of Comey's letter to lawmakers?
No. Lynch objected to Comey's decision to notify Congress that the FBI was reviewing newly discovered email, an official familiar with the matter told USA TODAY. Lynch based her objection on a long-held Justice Department policy that federal authorities should not take any action that may interfere with an election.
Did Lynch try to stop Comey?
Yes. Lynch shared her objections just hours before Comey sent the letter, according to USA TODAY's source. The FBI director weighed the attorney general's advice during a spirited discussion of the matter Thursday and early Friday, but in the end, Comey felt compelled to act.
When is the election?
Tuesday, November 8.