Earlier versions of macOS

1. Choose Apple menu > System Preferences, then click Security & Privacy.
2. Click the FileVault tab.
3. Click the lock  and enter an administrator name and password.
4. Click Turn On FileVault and follow the instructions.

macOS Ventura or later

1. Choose Apple menu > System Settings.
2. Click Privacy & Security in the sidebar.
3. Scroll down to the FileVault section on the right, then click Turn On and follow the instructions.