There have been a lot of incremental changes, but the big one was "Firefox Quantum" in November 2017 https://blog.mozilla.org/blog/2017/11/14/introducing-firef

There have been a lot of incremental changes, but the big one was "Firefox Quantum" in November 2017 https://blog.mozilla.org/blog/2017/11/14/introducing-firefox-quantum/ https://blog.mozilla.org/blog/2017/11/14/introducing-firefox...