WhatsApp rolled out a two-step verification feature for users of beta version 2.16.341 and above in its Account Settings, last year in November. The feature aims to defend users against cyber criminals, who might try to clone their device.
WhatsApp users can initiate this optional feature by doing the following...
>> Go to Settings
>> Click on Account
>> Selecting Two-step verification
>> Turn on Enable
According to WhatsApp's official FAQ page, when a user has two-step verification enabled, "any attempt to verify your phone number on WhatsApp must be accompanied by the six-digit passcode that you created using this feature."
Users can also optionally provide their email address after this feature is enabled, which will allow WhatsApp to send a link via email to disable the two-step verification in case they forget their passcode.
WhatsApp users were also warned on the FAQ page to not click on the link if an email is sent to disable two-step verification, without requesting it as it would be from a malicious party.
It's important to note that an user's number will not be allowed to reverify on WhatsApp without 7 days of last using the client if two-step verification is enabled.
To help users remember their passcode, WhatsApp would periodically ask them to enter it and there's no option to disable this without disabling the two-step verification feature.