New Delhi, June 19 -- Chatbots are employed every day as teachers, counsellors, coders and escorts. Now they are taking on another role: salesmen. Advertisements are popping up ever more frequently in users' conversations with large language models, punctuating chats with promotions. Consumers' search queries, editing sessions and even intimate moments are increasingly at risk of interruption by sponsored messages.

As chatbots become adbots, the future of two industries is at stake. For the artificial-intelligence business, ads represent a way to monetise a wildly expensive invention that most people currently use free of charge. For the ad industry, adbots are a possible answer to the existential question of how advertising will work if...