People often compare the brain to a computer, but the brain doesn't have USB slots that allow you to pick up new information by jamming a flash drive in your ear. That would be convenient if a little painful.
So where do we get all this information sloshing around in our skulls? You might imagine human memory is a bit like a Santa's sack filled with life events, song lyrics, and the first half of jokes. But in truth, "memory" is not one single solid thing. It is a term covering lots of types of recollections that are surprisingly distinct and used constantly in different combinations by a typical human.