https://www.cnet.com/news/firefox-to-block-some-technology-that-tracks-you-on-the-web/

Firefox, a browser billing itself as the choice for anyone valuing privacy on the web, is following rivals that led the way with a technology called tracking protection.

With the 2017 release of Firefox 57 -- the first "Quantum" version geared to reinvigorate Firefox's competitiveness with Google's Chrome -- Mozilla made it possible to block website software that tracks you on the web. Trackers can be used so advertisers can build detailed profiles of you and show you an ad that follows you around the web. Trackers also mean websites load more slowly, use your network data and consume more battery power.