Search engines, social media, e-commerce, and mobile games all make money by selling advertising. But making ads work in AI search might not be so straight forward. Perplexity, for instance, reportedly pulled back on plans to integrate ads into their AI search engine. And internal documents showed the company made only $20,000 in ad revenue in the fourth quarter last year.

Marketplace’s Meghan McCarty Carino spoke with Garrett Johnson, professor of marketing at Boston University to get a sense of why jumping into the ad business is difficult.