How ads follow you around the internet

Hint: It’s why every site asks you to accept cookies.

You’ve seen the pop-ups: “This site uses cookies to improve your experience. Please accept cookies.”

It’s true, cookies do improve your experience. They function as the website’s short-term memory. With each new click you make, cookies help the site identify you as the same person. Imagine every time you add something to your cart and click away, it disappears. Or each time you load a new page on Facebook, you have to log in again. Without cookies, the online world we know today wouldn’t exist.

But that world relies on advertising, which gives three kinds of companies a strong incentive to repurpose cookies to track your online behavior. Brands want to sell products by serving you ads for things you’re likely to buy. Platforms and publishers want to make money by serving those ads when you’re on their site. And middlemen are in the business of ensuring the ads from the brands are delivered to the right people.

A building block of our online world has become a tool to track you wherever you go in it. And now that browsers like Safari and Firefox are fighting back, the digital advertising industry is looking for new ways to follow you online.

In this video, we explain how cookies work and what you should know about how they’re being used. We even get a little help from the man who invented them.

You can find this video and all of Vox’s videos on YouTube. And join the Open Sourced Reporting Network to help us report on the real consequences of data, privacy, algorithms, and AI.

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