- Option – Boot directly to the Startup Disk manager
- Command+R – Boot into Recovery Mode of OS X (modern versions of OS X only)
- C – Boot from a CD/DVD
- T – Boot in Target Disk mode (FireWire or ThunderBolt only)
- N – Boot from an attached network server (NetBoot mode)
- X – Attempt to force Mac OS X to boot
- Shift - Boot up in ‘Safe Mode’ which has limited functionality but disables third party extensions
- Command+V – Boot into Verbose mode
- Command+S – Boot in Single user mode