Headless browsers - the behind-the-scenes software that lets machines surf the web like people - were once the domain of quality-assurance testers and SEO agencies. But new AI-powered browsers launched this last year - like Perplexity's Comet and Browser Company of New York's Dia - are bringing new meaning to the term. These players are using headless browsers to power AI agents that need to click, scroll and interact with websites as a human would, to retrieve information.