Run-Level 0 = Halt the system. Run-Level 1 = Single-user mode (for special administration). Run-Level 2 = Local Multiuser with Networking but without network service (like NFS) Run-Level 3 = Full Multiuser with Networking Run-Level 4 = Not Used Run-Level 5 = Full Multiuser with Networking and X Windows(GUI) Run-Level 6 = Reboot.