How does FileVault work on a Mac?
If you store sensitive information on your Mac—for example, if you carry your company’s financial data on your Mac laptop—you can use FileVault to protect your files and keep someone from accessing or copying sensitive data.
If you have a Mac with Apple silicon or an Apple T2 Security Chip, your data is encrypted automatically. Turning on FileVault provides an extra layer of security by keeping someone from decrypting or getting access to your data without entering your login password.
To ensure security when you turn on FileVault, other security features are also turned on. For example, when you turn on FileVault, you need to enter a password to log in when your Mac wakes from sleep, or after leaving the screen saver.
After an administrator turns on FileVault, any user with an account that has FileVault turned on can start up your Mac and log in with their password. If a user has an account that doesn’t have FileVault turned on, another user with an account that has FileVault turned on must start up your Mac, log in, then log out (but not restart). Then, the user with an account that doesn’t have FileVault turned on can log in. See Protect data on your Mac with FileVault.