-Nagios-mode is an Emacs mode for editing Nagios[1] configuration
-files. You probably already know that, or you wouldn't be reading
-this. But maybe you just love Emacs, and you go around looking for
-things that end in -mode. Then you README them.
+Nagios-mode is an Emacs mode for editing Nagios configuration
+files. Nagios is monitoring software that is configured via plain-text
+(*.cfg) files. Those configuration files have a C-like syntax, and a
+bunch of special keywords. Witin Emacs, nagios-mode will apply syntax
+highlighting to them, possibly alerting you to the fact that you have
+done something wrong, and making your buffers look pretty in any case.