Flashback allows you to take the user interface, used for real-time monitoring, back to a point-in-time of the recent past (i.e. yesterday at 10:00, or last week at this time).
You can jump directly to a time in the past, then navigate forward or backward by a minute, or several minutes, or even 10 seconds. All windows are updated to the point-in-time, allowing you to correlate metrics from multiple windows.