How to enable WhatsApp's two-step verification

WhatsApp is adding an extra security feature to help keep its more than a billion users safe from hacks. The company is rolling out two-step verification to its users worldwide.
When it’s available you will find it in the messaging service’s app under Settings > Account > Two-step verification > Enable.
WhatsApp’s approach to two-step verification differs from what other online services such as Facebook or Google do. Instead of using an app that generates one-time pas