What key combination is used to initiate a recovery startup on a Mac?

The key combination used to initiate a recovery startup on a Mac is Command-R. This specific combination allows the Mac to boot into macOS Recovery, a built-in recovery system that can be used for troubleshooting, reinstalling macOS, restoring from a Time Machine backup, and accessing various utilities like Disk Utility.

When you use Command-R at startup, the Mac will attempt to load the version of macOS that was installed on the system at the time of the last update, providing users with a convenient way to troubleshoot or restore their system without needing external media. This is particularly useful when a Mac is experiencing issues or requires a reinstall of the operating system without completely wiping the drive.

The other options, while related to recovery or startup processes, lead to different results. For instance, Command-Option-R is used for Internet Recovery, which can install the latest compatible version of macOS. Command-S is the shortcut for single-user mode, which is primarily used for advanced troubleshooting via command-line. Option-R is similar to Command-Option-R but may not always provide the same capabilities, particularly regarding network recovery. Each combination serves specific functions in managing the startup process but only Command-R directly initiates the standard macOS Recovery environment.