Hillary Clinton receives intelligence briefing by FBI
Traditionally, the top two contenders for the White House are given the briefings to prepare them for the responsibilities that await the next occupant of the Oval Office.
Republican candidate Donald Trump attended a similar briefing August 17 in New York, accompanied by two key advisers, retired lieutenant general Michael Flynn and New Jersey Governor Chris Christie.
Clinton was alone for her briefing, which took place at the Federal Bureau of Investigation's White Plains, New York office, near her home in Chappaqua, an aide told reporters.
The aide said she met with a handful of officials from the Office of the Director of National Intelligence for about an hour and a half.
The FBI's office was used because it has secure rooms in which classified information can be discussed.
The tradition of intelligence briefings for presidential candidates began in 1952 under president Harry Truman.
The briefings lay out the US intelligence community's view of the threats facing the United States, without divulging secrets about operations or sources.
Democrats have expressed unease about Trump's access to such sensitive information, with President Barack Obama himself issuing a thinly veiled warning earlier this month.
"If they want to be president, they have got to start acting like (a) president," he said in a clear reference to the unpredictable New York billionaire.
"That means being able to receive these briefings and not spreading them around."