Manually restart: Power (⎋)
Boot from CD/DVD: C
Startup Manager: Option (⌥)
Single-User Mode: Command (⌘)—S
Target Disk Mode: T
Verbose Mode: Command (⌘)—V
Safe Mode: Shift (⇧)
Recovery OS: Command (⌘)—R
Internet Recovery OS: Command (⌘)—Option (⌥)—R
Apple Hardware Test: D
Apple Hardware Test over the Internet: Option (⌥)—D
Boot from NetBoot server: N
Boot from NetBoot server using the default image: Option (⌥)—N
Eject removable media: Media Eject (⏏), F12, mouse button or trackpad button
macOS Startup Volume: X will start up your Mac from an macOS startup volume when it’d otherwise boot from a non-macOS volume, like a Windows partition
Prevent Login Items from opening: To override your current settings and prevent Login Items and Finder windows from your last session from opening when you log in, hold down the Shift (⇧) key after clicking the Log In button in the macOS login window until the desktop appears.
Prevent automatic login: If you enabled the option to automatically log a specific macOS account every time your Mac starts up, you can override this setting by holding the left Shift (⇧) key after the macOS boot progress indicator appears.
Reset PRAM/NVRAM: Command (⌘)—Option (⌥)—P—R, then release the keys after you hear the startup sound for a second time
Reset SMC: Shut down your Mac, and then press and hold the left-side Shift (⇧)—Control (⌃)—Option keys along with the Power (⎋) button, all at the same time, until the computer turns on. Now release the keys and then turn your Mac back on using the power button.