Mozilla has started rolling out DNS over HTTPS for all Firefox users, a solid security change that’s meant to address the issue of third parties spying on the websites you’re visiting. Normally, when you type a website into your browser’s address bar and hit Enter, your browser uses DNS to map the domain name to the actual IP address of the server you’re trying to reach—the one that hosts the website you’re looking to visit.
DNS queries are typically unencrypted, which means that these requests can “leak” and be easily intercepted by a third party. This allows everyone from hackers to advertisers to easily view what websites you’re trying to visit, even if the sites themselves are encrypted (HTTPS). As the Center for Democracy and Technology describes: