Two-Factor Authentication
Apple Account Access & Authentication
Essential
Turn on two-factor authentication for your Apple Account.
What this setting does
Two-factor authentication adds a second layer of protection to your Apple Account. Even if someone obtains your password, they still need a verification code from one of your trusted devices or trusted phone numbers before they can sign in on a new device or on the web. Apple describes two-factor authentication as the default security method for most Apple Accounts.
Important notes
Two-factor authentication requires at least one trusted phone number that can receive verification codes. Your trusted devices can also display verification codes when you sign in somewhere new.
After a device successfully signs in using two-factor authentication, it becomes a trusted device and normally does not require another verification code unless you sign out, erase the device, or make certain security-sensitive account changes.
Most Apple Accounts already use two-factor authentication. Certain Apple services and stronger security features also require it.