State Partitioning is an interesting privacy feature shipping with Firefox 86.
With State Partitioning, shared state such as cookies, localStorage, etc. will be partitioned (isolated) by the top-level website you’re visiting. In other words, every first party and its embedded third-party contexts will be put into a self-contained bucket.
Applies to every embedded third-party resource (regardless of whether it is a tracker or not), but some exceptions for Single Sign-On purposes have been made.
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.
I spent some time talking to a reporter yesterday about how advertisers track people on the internet. We had a really fun time looking at Firefox’s developer tools together (I’m not an internet privacy expert, but I do know how to use the network tab in developer tools!) and I learned a few things about how tracking pixels actually work in practice!