Startup key combinations for Intel-based Macs

By Richard Mallion
There are now quite a few different combination of keys you can hold down at startup that effects the way your Mac boots, so here is a useful summary.
Press C during startup:  Start up from a bootable CD or DVD, such as the Mac OS X Install disc that came with the computer.
Press D during startup:  Start up in Apple Hardware Test (AHT).
Press Option-Command-P-R until you hear two beeps:  Reset NVRAM
Press Option during startup:  Starts into Startup Manager, where you can select a Mac OS X volume to start from. Note: Press N to make the the first bootable Network volume appear as well.
Press Eject, F12, or hold the mouse or trackpad button:  Ejects any removable media, such as an optical disc.
Press N during startup:  Attempt to start up from a compatible network server (NetBoot).
Press T during startup:  Start up in Target Disk Mode.
Press Shift during startup:  Start up in Safe Boot mode and temporarily disable login items.
Press Command-V during startup:  Start up in Verbose mode.
Press Command-S during startup:  Start up in Single-User mode.
Press Option-N during startup:  Start from a NetBoot server using the default boot image.
Press Command-R during startup:  Start from Lion Recovery