One of the coolest things ever and I never would have thought of it. I'm no programmer but after needing to re-login to everything once I assigned containers, my observation is each container is essentially a separate instance of the browser, each container with its own set of cookies. This is a genius way to split up cookies based on how sensitive the info is, and it somehow manages to run as if I didn't install an addon that does multi-process instances in one window. I've been using Firefox ever since I started to understand cybersecurity from wiki dives and debit card fraud in high school and would just like to say this is probably the most customizable, resource-efficient/multithreaded/fast and private browser there is. That's why I have my beta studies turned on now; I want to contribute. Thank you and keep up the great work over there!