Solaris Run Level

Run Level	Init State	Purpose
0	Power-down	Shut down the operating system so that it will be safe to turn off the power to the machine.
S	Single-user	Run the system in a single-user mode with some file systems mounted and accessible.
1	Single-user administrative	Run the system in a single-user administrative mode with all available file systems accessible but user logins disabled.
2	Multiuser	Run the system in multiuser mode. Multiple users can log in, all file systems are accessible, but the NFS daemon is not running.
3	Multiuser with NFS	Run the system in the standard mode: normal operations allowed, NFS used to share resources. Default run level.
4	Alternative multiuser	Unused by default, but you can define it according to your needs.
5	Power-down	Same as run level 0; in addition it will automatically turn off the power if the hardware supports that.
6	Reboot	Shut down the system to run level 0 and then reboot it to the default run level specified in the inittab file