Two-factor verification is an added layer of security that makes your account accessible only on devices you trust, like your iPhone,iPad or your Mac. When you need to sign into a new device, you are not only asked for your regular passcode, but you also need to enter a unique 6 digit verification code that gets automatically displayed on your trusted device. By entering the verification code, you certify the device as a trusted device and automatically verify it. As an example, if you already have an iPhone and have Two factor authentications enabled for your Apple ID and you try to login to your newly purchased iPad or Mac, then a unique verification code gets displayed on your iPhone which you will give to enter on the new device to certify it as a trusted device and log in to it.
As the password is not the only credential required to access your account, the security concerns are drastically reduced, and the device is marked trusted once you enter the verification code meaning that you won’t have to verify the device again unless you totally wipe it. However, in the case of a browser login, you are given an option to trust the browser or not to.
A trusted device is an iPhone, iPad or and iPod running iOS 9 or a newer version or a Mac with OS X El Capitan or newer that you’ve already verified and signed in using Two-factor authentication. It is a device that is trusted and known to be yours which can be used to display the verification code when you wish to login from a new device or a web browser.
Trusted Phone Numbers:
Trusted phone number is a number that is verified and one which can be used to receive the unique 6 digit verification code. To enable two-factor authentication it is mandatory to have at least one phone number verified, however, it is recommended to have more than one phone number verified, like your home phone or the phone number of your trusted friend so that you can still access your Apple ID in case your phone isn’t accessible.
A verification code is a temporarily generated unique code that gets expired after a given amount of time. This code is used to verify the newly added device as a trusted device so and login to it. This is automatically shown on already verified devices and can also be obtained from the settings section of the verified device.
Turn on Two-Factor authentication on iOS:
To enable Two-Factor authentication, you need to be an iCoud user with at least one device having iOS version 9 or above or a Mac running OSX El Capitan or above.
If you’re using iOS 10.3 or later then Start off by firing up the Settings > [your name] and select Password & Security. Here tap to Turn on the Two-Factor Authentication for your Apple ID and tap Continue.
If you’re using iOS 10.2 or earlier then first go to Settings and select iCloud. Now tap on your Apple ID and select Password & Security. Here you should find Two-Factor authentication settings, tap Turn on Two-Factor Authentication to turn it on and then tap Continue.
Now enter a trusted phone number that you want to receive the verification codes on, you can choose to receive the verification code by text or by a call. On tapping the next option, Apple would send out a verification code to the given phone number either by SMS or by the call as selected before. Enter the received verification code to verify the number and enable Two-Factor authentication.
Follow these steps on your Mac with OS X El Capitan or later:
First, go to Apple menu and select System Preferences and then click on the iCloud tab and choose Account Details. Then click on Security and click to Turn on Two-Factor Authentication for the Apple ID. Most Apple ID’s that were created in iOS 10.3 and above or Mac OS 10.12.4 or newer have Two Factor Authentication enabled by default, in this case, you can see the option already turned on.