WhatsApp's extremely high user engagement and rapid growth are driven by the simple, powerful and instantaneous messaging capabilities we provide.

As long as our user base continues to grow, at some point it will have critical mass, and at some point it will tip, and at some point, people will just have to use WhatsApp because their friends are using WhatsApp.

The message growth rate in Brazil - it's not like a hockey stick: it's like a vertical line.

At WhatsApp, our engineers spend all their time fixing bugs, adding new features and ironing out all the little intricacies in our task of bringing rich, affordable, reliable messaging to every phone in the world. That's our product, and that's our passion. Your data isn't even in the picture. We are simply not interested in any of it.

'WhatsApp' began as a simple idea: ensuring that anyone could stay in touch with family and friends anywhere on the planet, without costs or gimmicks standing in the way.

I had so much fun in early days learning about networking, security, scalability and other geeky stuff.