Mozilla has begun enabling a Firefox privacy feature for everyone in the US that should make it harder for ISPs or others to track you online. The technology, called DNS over HTTPS (DOH), protects a crucial internet addressing technology with encryption.

Mozilla has tested DOH for months, but on Tuesday will start enabling DOH for everyone in the US. The gradual spread to all Firefox users should take a few weeks as Mozilla checks for problems. 

DOH fits with a tech industry shift toward privacy that has been triggered by data breaches, digitalization of our lives and issues like Facebook's Cambridge Analytica scandal. Mozilla has long championed privacy, and Apple has made it a major priority. Even Google and Facebook, online advertising giants that make money by following you around the web, are trying to adjust.

"DNS over HTTPS has the potential to close one of the largest privacy gaps on the web," said Max Hunter, an engineering director at the Electronic Frontier Foundation, an online privacy group, in an earlier blog post.

DNS is a decades-old addressing technology. Every server on the internet has a numeric address used to route data, but when we're using a website, we'll type in an address like "www.cnet.com." DNS looks up the numeric internet address so browsers can load the website. 

Typical DNS address lookups aren't encrypted, which exposes them to anyone handling your network traffic -- your ISP, hotel or airport Wi-Fi service, or a government agency or criminal that can snoop network traffic. ISPs, which often handle DNS duties, can sell your browsing history.

DOH, which Mozilla pioneered, encrypts the DNS address lookup to shield it and to protect against tampering. It's won support from Google's Chrome team and privacy-focused browser maker Brave (and opposition from UK ISPs that briefly nominated Mozilla for an Internet Villain award).

But some fear DOH is a step backward. Notable critics include Paul Vixie, who helped create DNS, and Bert Hubert, creator of the PowerDNS software. One concern is that DOH could centralize DNS activity; another is that it could offer companies a new way to track you online.

Firefox offers two DOH service choices, Cloudflare and NextDNS, and requires DOH partners to follow a privacy policy barring sales of DNS data. It has no plans for now to offer DOH in Europe, meaning Firefox users there won't have their DNS data handled by a US company.

Chrome is taking a less active DOH stance than Firefox. There, DOH is still experimental and is used only when your existing DNS setup offers it.