The /boot directory contains all files needed to boot the computer. These files don’t
change very often. On Linux systems you typically find the /boot/grub directory
here. /boot/grub contains /boot/grub/grub.cfg (older systems may still have /boot/
grub/grub.conf) which defines the boot menu that is displayed before the kernel
starts.
All of the machine-specific configuration files should be located in /etc. Historically
/etc stood for etcetera, today people often use the Editable Text Configuration
backronym.
A lot of Unix/Linux distributions have an /etc/init.d directory that contains scripts to
start and stop daemons. This directory could disappear as Linux migrates to systems
that replace the old init way of starting all daemons.
