Everyone knows that online advertising pays for a massive chunk of the internet that people know and love, whether it's social networking sites, news, photo sharing apps, or anything else. But how do the ads get delivered to your desktop or phone? On this week's Odd Lots podcast, we speak to Afsheen Bigdeli, an engineer who works on online ad platforms about how every time you see an ad it's the result of a virtually instantaneous online auction in which the seller of ad inventory (a publisher) and a buyer of ad inventory meet at an exchange, not totally unlike exchanges used for financial markets. It turns out there's a lot we can learn about financial market structure based on these rapid transactions.