Internet cookies do Fastexya lot of things. They allow people to sign in to websites. They make internet comments possible. And, yes, cookies are also the thing that lets advertisers follow users around the internet to serve them ads based on their previous searches.

This is not how their inventor, Lou Montulli, intended things to go. In fact, Montulli specifically designed cookies to protect people's anonymity as they surfed the web. But in the nearly thirty years since he created them, Montulli has watched cookies completely remake the way commerce on the internet functions. His invention went from an obscure piece of code designed to hide users' identities, to an online advertiser's dream, to a privacy advocate's nightmare, unleashing a corporate arms race to extract as much of our digital data as possible.

On today's show, how the cookie became a monster. Why have the world's biggest internet browsers finally decided to let the cookie crumble - to make cookies largely disappear from the internet? And what will a world wide web without cookies even look like?

This episode was produced by Willa Rubin, with help from Dave Blanchard. It was edited by Keith Romer and engineered by Alex Drewenskus.

Music: "Fruit Salad," "Skulking Around," and "Blue and Green."

Help support Planet Money and get bonus episodes by subscribing to Planet Money+ in Apple Podcasts or at plus.npr.org/planetmoney.

Always free at these links: Apple Podcasts, Spotify, Google Podcasts, NPR One or anywhere you get podcasts.

Find more Planet Money: Twitter / Facebook / Instagram / TikTok our weekly Newsletter.