Upto solaris 9 runlevel are used they are

Runlevel 0 1 2 3 4 5 6

In solaris 10 milestone is introduced. Milestone is

improved level of runlevel

In run level we use init 1 to bring system into single

user, in milestone # svcadm milestone single-user command

used to bring the system to single user Simillarly

init 2 as multi-user(more than one user),init 3 as multi-

user-sever provide multiuser mode along with nfs

runlevel 4 is currently unused

runlevel 5 ie init 5 shutdown and power off

runlevel 6 ie init 6 shut down and restart