FileVault is Apple’s built-in volume-encryption feature for macOS. It encrypts the startup disk so the data on a Mac stays protected when the device is powered off, stolen, or accessed by someone who does not have the login credentials or recovery material. In practice, FileVault is a form of full-disk encryption for endpoint defense.
In cyber security, FileVault matters because it reduces the value of a lost laptop and makes offline disk access much harder for an attacker. It is commonly enforced through device-management tools, with recovery keys escrowed for administrators so access can be restored after a password loss or hardware failure. The main operational risk is not the cipher itself, but poor management: if FileVault is not enabled consistently, or if recovery keys are exposed, the protection weakens. Used well, it is a strong control for data-at-rest protection on macOS fleets.