Fewer than one in four people in India have a smartphone, but in a country of more than 1.3 billion, that's about 300 million. And as of February 2017, 200 million of them are on WhatsApp - texting, voice messaging and video-calling each other - making India the messaging service's biggest market.

But India's WhatsApp habit has a dark side too. Misinformation, disinformation, rumours and false messages can go viral. In at least two cases, fake messages spread on WhatsApp have led to mobs lynching innocent people.