WhatsApp has rolled out two-step verification for all its users. The feature, which was previously in beta for Android, now works on all platforms.
Two-step verification adds a six-digit passcode to your login information, so when you attempt to log into WhatsApp on another device you’ll need that passcode alongside your phone number. To enable two-step verification, open WhatsApp, then tap Settings > Account > Two-step verification > Enable. You can optionally enter an email address here that allows you to disable two-step verification if you ever forget your passcode.