Each primary stage of system initialization can be indicated by the following: firmware, startup chime...

Each primary stage of system initialization can be indicated by the following: firmware, startup chime or bright flash of the power-on light, followed by a light gray screen on the primary display; booter, a dark gray Apple logo on the primary display; kernel, a small dark gray spinning gear or spinning earth icon below the Apple logo; and system launchd, a white screen on all displays followed by the login screen.