New Delhi, Oct. 2 -- A simple 'thumbs-up' emoji can change the course of a conversation. You send a message, wait for a response, and there it is. One tiny thumb. It can signal happiness, agreement, understanding, or simply fill an awkward silence when words fail. For many of us, especially those who didn't grow up swiping tiny screens, it is both a lifeline and a puzzle. Is it saying 'I'm thrilled,' 'I hear you,' or 'I have no idea what to say, so here's a thumb'?

The thumb has become the Swiss Army knife of digital communication. We deploy it everywhere: WhatsApp groups , Slack threads, even emails. We use it when we're happy, when we agree, when we don't know what to say and also when we just want to look polite without committing any...