This is an ad-blocker add-on that uses host matching instead of RegExp matching to increase performance and reduce memory usage. When a new resource is requested, the extension matches its hostname to the list of the known advertisement or analytic sources. If the hostname is on the blacklist, the request gets blocked. If not, it will load as usual. You can extend the default list by adding your custom domain names in the backlist text box or whitelist a top domain by adding its hostname into the whitelist textbox. The default blacklist hostnames: https://adaway.org/hosts.txt https://hosts-file.net/ad_servers.txt https://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&showintro=0&mimetype=plaintext Before adding a new hostname to the list, make sure to check the current state of the hostname by inserting the hostname in the evaluation input box. Difference between this extension and other ad-blocker extensions: Extensions like uBlock Origin or AdBlock Plus use RegExp matching, which is more powerful but slow in performance. This one only uses exact host matching. Since some websites still inject inline scripts, it is recommended to install a popup blocker along with this extension.