After being tested in beta on Android, WhatsApp is rolling out 2-factor verification worldwide on both Android and iOS now, via a server-side update. Because WhatsApp is phone number-based, the way this works is different from other two-step processes for securing accounts.

While it is different, it's a neat process for securing an account. If logged in to WhatsApp, in Settings there is an option saying 'Two-step verification.' Turning this on will prompt the app to ask for a six digit passcode that is used whenever registering your phone number with WhatsApp. Enter this twice, then a backup email in case you forget said passcode, and you're done. Whenever your phone number is entered into WhatsApp's setup process, it'll ask for the six digit passcode, thus securing your number from unscrupulous hackers attempting to take advantage. To help you remember the passcode, WhatsApp will ask "periodically" for it; certain team members say it looks like this will be weekly, according to the beta.

The email you entered is used as a backup; in case you are locked out of your account, WhatsApp will email you a passcode reset. However, this email is not checked for accuracy, so make sure it's correct when entered.

This is rolling out to all WhatsApp accounts worldwide now. WhatsApp is available on the Google Play Store, or we have it at APK Mirror if you'd prefer.

Source: WhatsApp FAQ

Thanks: Mahmoud Itani