Boy was I surprised when I saw so many cookies from the g00.msn.com domain saved on my computer. In case you don't know, those cookies are put there by InStart and occurs on many other websites that have advertising and not just the one in my screenshot. To see the effect just go to a website with lots of advertising like msn.com or boston.com. I wrote this extension that monitors cookies with ".g01." in the domain name and makes their cookies expire after a few minutes. Click on the toolbar icon to see what cookies on your computer currently have ".g00" in the domain name. So why not block the cookies altogether? Because you never know what their code is doing and blocking it might potentially cause infinite loops. The more passive approach is just to allow it but make cookies expire quickly. Plus it is impossible for them to know when cookies are set to expire so it is a secret way of doing it! Further reading: https://www.theregister.co.uk/2017/08/11/ad_blocker_bypass_code/ https://github.com/gorhill/uBO-Extra/wiki/Sites-on-which-uBO-Extra-is-useful