When the system starts the file /boot is read, it then reads /unix (it is the program for the UNIX kernal itself).
The following shows some directories which reside in root and its contents.
/bin : basic programs like who,ed reside.
/etc/rc : This is a file of shell commands which is executed after the system is bootstrapped.
/etc/group : lists the members of each group.
/lib : Contains the parts of the C compiler.
/tmp : Contains temporary (short-lived) files that are created in the execution of programs.