Do you want to boot into Mac OS X verbose mode? Well, Verbose mode is useful when troubleshooting Macs. Generally developers use this mode. But you can also boot into Mac OS X verbose mode. It can be fun to look at the underpinnings of Mac OS X. If you want to boot into Mac OS X verbose mode then simply hold down Command+V immediately after reboot or after powering on your Mac. Then you will be able to see lots of text reminiscent of the command line as you can see from the image posted below. This indicates that you are in verbose mode.
When you are in verbose mode you will not be able to see the standard Mac OS X boot screen. You should note that you can set your Mac to always boot in verbose mode or simply hold down the key combination so that your next reboot will be normal again.