While most people haven’t heard of AppNexus, many Internet users almost certainly interact with the company on a daily basis. AppNexus is an exchange that allows advertisers to bid for the ability to sell products to users online — 13 billion times a day.

“When you go to any website on the Internet, it looks like all of the the text and the ads load at the same time, but the ads actually load a blink of the eye later,” CEO Brian O’Kelley says. “In that blink of the eye, we hold an auction to see which advertiser will pay the most for the chance to serve you an ad.”

AppNexus bases prices off of a variety of factors including time of day and user data. Cookies are used to track which users have seen which ads and how recently.

O’Kelley says the industry currently relies on self-regulation rather than government oversight.

“It would be great if the industry could find the right way to balance between monetizing websites and the expectations of consumers,” O’Kelley says. “The service we are providing to the Internet is keeping it free to consumers.”

To hear more about regulation and how AppNexus works, click on the audio player above.