You can virtually add any domain to a list. When you try to visit the website it'll redirect you a simple HTML page stating what was blocked. That is assuming you have added the domain to the list. There are two ways to block a domain. You can go to the extensions HOME/options page to manually add the domain (in the correct format). Or you can click on "ADD DOMAIN" within the extension's popup page. Format consist of any number of subdomain + domain + top level domain. For example store.google.com OR google.com. Blocking store.google.com WILL NOT block google.com. However, blocking google.com WILL block store.google.com. Sometimes, ad blockers don't block everything on a website. By manually adding the domain of the ad you should be able to block it. For backup purposes, you will be able to download your list as a simple text (.txt) file. You can also import that same text file in case your list is somehow lost. Just know that importing the text file will overwrite any current existing list. Also note that there is no database connected to this add-on. Everything is saved locally. Which is why you should download your list every so often. The easiest way to view the extension's HOME/options page in its entirety is to click on "HOME" button within the extension's popup page. You can also do this within the context menu (right click on a page). This is just a fun small side project to put on my resume. Icon from juicy_fish https://www.flaticon.com/authors/juicy-fish https://www.flaticon.com/free-icons/defensive-wall