Please explain this like I'm 5 years old, as I'm not car-savvy at all.

I currently own a car that my dad bought in 1999, and has never left the family.  It's been serviced in both the dealership shop and some mom-and-pop oil change type places.  Would I get anything out of a CarFax or AutoReport check?  Maybe even an idea of what the outside world thinks of the car, compared to the detailed service records that we keep ourselves in an Excel spreadsheet?

I'm interested, especially since I may need to trade in my car soon.  I know what's been done to the car, but how much does the outside world know?  That *I* don't know.