What is in it?

The intelligence community tailors the P.D.B. to each president’s interests and style of absorbing information. At times, the briefing has included a “deep dive” into a specific question that a president may have asked or information that briefers believed he needed to know, such as the early August 2001 briefing Mr. Bush received at his Texas ranch reporting that Osama Bin Laden was determined to strike inside the United States. After the Sept. 11, 2001, attacks, Mr. Bush received a supplement called the “threat matrix,” which listed more detailed intelligence about potential terrorist plans. Under Mr. Obama, the brief has taken on some new topics and different forms, including a periodic update on cyberthreats against the United States. The P.D.B.’s form has also evolved. For example, Mr. Bush preferred oral briefings to accompany the document, while Mr. Obama has preferred to read the briefing on a secure tablet computer that lets him page through underlying specific details.

Is it dangerous not to receive it each day?

Several former senior intelligence officials said that getting the briefing every day is not strictly necessary, especially if Mr. Trump delegates substantial amounts of authority to his subordinates. But they stress that regular briefings are still important because it is helpful in a fast-moving crisis if a president already has a baseline of knowledge about topics, such as a foreign leader’s thinking and military abilities. Also, briefings permit a president to quiz briefers on inconsistencies and questions of fact or interpretation that form the basis for the most important national security decisions — those only the president can make.

Matt Olsen, the former director of the National Counterterrorism Center, said that “it’s critical for the president to get an intelligence briefing, if not every day, almost every day” rather than just checking in periodically.

“Ultimately these decisions come to the president, so as much as you could rely on staff to track intelligence, you are being called on constantly to make operational decisions that put American lives in jeopardy,” he said.

Why might it seem boring?

One possible problem, said Andrew Liepman, a former senior C.I.A. official who helped write P.D.B. entries on the Middle East and terrorism for several presidents, is that the intelligence community has developed a formulaic and repetitive style of writing. The reason, he said, is policy makers wrestling with difficult dilemmas have tended to seize on any variations in analysts’ wording as meaning that something significant must have changed — even if nothing has.