In MacOS, disk encryption is implemented by enabling the FileVault feature. FileVault is a disk encryption program available in Mac operating systems that uses XTS-AES-128 encryption with a 256-bit key to help prevent unauthorized access to information on the startup disk. It's designed to encrypt the entire drive on your Mac, protecting your data with a password and automatically encrypting everything stored on the Mac. This feature is particularly important for users who handle sensitive information and want to ensure that their data is secure, even if their computer is lost or stolen.