How ads follow you around the internet

A video-version of How tracking pixels work by Vox:

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

Spot on “Finding Dory” analogy. One thing where they do go off a bit is that they somewhat imply that all data (such as shopping cart contents) is stored in the cookies themselves. That’s not the case: the cart contents are – or at least they should be – stored on the server. Only the cart’s ID (or your visitor/session ID) is stored in the cookie. The serverside code will then use that ID to get your card contents.

Also: would have loved to see a few examples with actual mentions of domain names to have it more clear.