Using its new method of handling cookies, Firefox Strict Mode can prevent hidden privacy violations and allow you to see which websites are storing information on your computer. When you elect to forget a website, Firefox will automatically delete all cookies, supercookies, and any other data stored on your machine.

With traditional cookie deletion techniques, third-party cookies can sometimes stick around when you try to delete them. That’s because websites will often use cross cookies, so deleting data from the site you’ve visited doesn’t necessarily delete all data it has stored.

With this new method from Firefox, all cookies from a website are stored in a single “cookie jar,” and when you empty that jar, all data is deleted, even those pesky cross cookies.

Without this feature, a site could use the cross cookie to track you through another website, even though you deleted its cookie. With it, all cookies are deleted, preventing future tracking (until you visit again and receive more cookies). Of course, you always have the option of blocking cookies completely, if you really want to lock things down.

To take advantage of this new form of cookie clearing, you’ll need to download Firefox 91. Once installed, turn on Strict Tracking Protection enabled in Settings. To turn it on, click the Shield next to any website. From there, click “protection settings.” Then, under Enhanced Tracking Protection, select “Strict.”

Once you have Strict mode enabled, Firefox will start putting cookies into “jars” rather than saving them to specific domains. If you want to delete a site’s data entirely, right-click a website on your history page and then click “Forget About This Site.”

When you clear a site in this way, you’ll be able to thoroughly remove all cookies, which will create a more secure experience for you.