High level description of postgres

Hi,

Can anyone give me directions to a high level descriotion of postgres? Which
executables and or scripts are there and what is their responsibility? What
is a typical scenario of what postgres does? Wait on a port listening for a
connection, on request fork? Is there a readable (and no, dozens of
Makefiles are not considered readable) list of dependancies? Which
executable depends on which source and /or libraries? Which library depends
on what othere librarie / source? etc. etc.

I have read (but not memorized) the user manual and the administrators
manual but I found them not giving the answers I was looking for.

TIA

Joost