Then press the Enable button which will display the setup screen, as shown above. This screen asks you to pick a six-digit passcode which will you be required to enter anytime you register your phone number with the app, including when you upgrade phones. Therefore, it is important that the passcode is memorable.

After choosing a code, WhatsApp will also let you pick a backup email address in case you forgot your code. If you do get locked out of your account, WhatsApp will be able to send a recovery email to this chosen address. Although optional, adding an email is recommended as a fallback in case you cannot remember your passcode. Note: do not click on links in emails unless you specifically request it from WhatsApp.

Now, when you setup a new device and install WhatsApp, it will ask for this six-digit passcode in order to validate your identity. WhatsApp will also periodically ask for this same passcode when you launch the app — this helps you remember your code. You cannot disable this reminder feature without disabling the entire two-step verification.

As an additional safeguard, WhatsApp will not allow you to verify your phone number within seven days of using the service without the passcode. This means if you don’t choose a recovery email, it will be impossible to verify your account without your code within seven days. After the seven day period has elapsed, you can access your WhatsApp account again (even without a code) but all messages will be deleted.

If your number is verified on WhatsApp after 30 days of not using a passcode, the account will be deleted entirely. If this happens to you, you will have to setup a whole new account and start from scratch.

Download WhatsApp for free from the App Store. Two-step verification is rolling out to all users now.