Security features on your MacBook Air
Your MacBook Air includes the Apple T2 Security Chip, which provides security features to protect what’s on your computer and prevent unauthorized software apps from loading during startup:
Secure storage: Your MacBook Air storage drive is encrypted with keys tied to its hardware to provide advanced levels of security. In the event of a catastrophic failure, data recovery may not be possible, so you need to back up your system to an external source. See the Apple Support article About encrypted storage on your new Mac. You can set up Time Machine or another backup plan to regularly back up the contents of your computer. See Back up your files with Time Machine in the macOS User Guide, and the Apple Support article Back up your Mac with Time Machine.
Secure boot and Startup Security Utility: Support for secure boot is turned on automatically. It helps ensure that only legitimate operating system software is loaded on your computer at startup. See the Apple Support article About Secure Boot.
If your MacBook Air doesn’t start because it detects an untrusted component, it will start up from a secure recovery partition and automatically correct issues if possible. To learn more about the Startup Security Utility or to find out how to set other options, such as starting up from an external device, see the Apple Support article About Startup Security Utility.
Note: In rare circumstances, such as a power failure during a macOS upgrade, MacBook Air may become unresponsive; the firmware on the chip may need to be revived. See the Apple Support article Revive firmware in Mac computers in Apple Configurator.
Learn more. See the Apple Support article About the Apple T2 Security Chip.