Keberos authentication is a bit of a top down concept. I'm working my way up to it from the bottom learning from the bottom up. It seems to me that Keberos authentication can be thought of as a glue between systems, so that you can authenticate from a single server for all the services / systems within a domain and don't have to store all of your login information multiple times. This isn't an easy concept to come across when you're working your way up from some low level like say....programming...
So what is this "area" between systems where Kerberos lives called?