A quick Google search of the "Presidential Daily Briefing" is really all you need. There's great wikipedia stuff on it, an official government page about it, plus a number of recent articles on who gets to see it and why. There were something like 30 Obama staffers that received it. Some Presidents attended every PDB personally, some rarely. The articles tend to take polar opposite views on the contents: either it is a Top Secret document (it actually is) that holds all the secrets to our national security, or it is a bland daily task that just tells you what changed in the Middle East (for example) from yesterday. That's why Trump doesn't read or attend the briefings; he says he "... doesn't need people telling him the same thing every day for 8 years."