India, Oct. 12 -- "Have you ever clicked your mouse HERE? You will."

That was the text accompanying the first banner ad on the internet, launched by telecommunications company AT&T on HotWired.com in 1994. The ad reportedly clocked a 44% click-through rate in its first four months, a figure that would be extraordinary by the standards of almost any digital marketing channel today.

Over three decades, online advertising has evolved from banner ads to search, social media, programmatic buying, influencer marketing and performance marketing.

Then, with the emergence of search engine optimisation (SEO) practices, brands started optimising websites, building backlinks, targeting keywords and creating content to improve their visibility. Ove...