asterisk.conf has two primary contexts, shown below with some descriptions about their content.
A Note on Includes
Includes in this file will only work with absolute paths, as the configuration in this file is setting the relative paths that would be used in includes set in other files.
[directories](!) astetcdir => /etc/asterisk astmoddir => /usr/lib/asterisk/modules astvarlibdir => /var/lib/asterisk astdbdir => /var/lib/asterisk astkeydir => /var/lib/asterisk astdatadir => /var/lib/asterisk astagidir => /var/lib/asterisk/agi-bin astspooldir => /var/spool/asterisk astrundir => /var/run/asterisk astlogdir => /var/log/asterisk astsbindir => /usr/sbin