What kind of employment history does a typical background check show?

I'm in the process of finding a new job right now. Just started digging into what kind of information a background check actually pulls up. I was originally under the impression that it was a criminal record that was the primary focus and maybe a check on driving history for applicable jobs. But I see now that on top of that a background check can also show employment and credit history too! This seems like a ridiculous amount of information that a potential employer gets access to. So I'm wondering if any hiring managers can answer what does this look like on your end? Do you see a month by month history of my previous employment history? Do you see all of my debts and open accounts?