1) Two-factor authentication Recently, WhatsApp rolled out two-factor authentication for its chat service. If you recall, there’s no username and password you need to use WhatsApp - you just need to type your phone number and verify it via an OTP SMS. If someone steals your phone, even if the phone is locked down, they could take out your SIM card and put it in a different phone. With just that much effort, they would have access to your WhatsApp account, as it would just require an SMS to verify the new phone. By enabling two-factor authentication, you can protect yourself from such fraudulent behaviour, as it will ask you to set a six digit passcode, which WhatsApp will ask every time you try to re-verify your account. And in case you forget your passcode, there’s a way to reset it via email too.