Ever since Mozilla adopted the fast updates policy, they are releasing a new version every few weeks. You start Firefox web browser and it starts updating to the new version. Sometimes the new version of Firefox has features that people do not like and want to revert back to the older version. And sometimes the new version of Firefox disables some of your favorite extensions because those extensions are not compatible with the new version of Firefox. If you are tired of these complications and want to work without any of these problems, then you should switch to the ESR version of Firefox.
Firefox ESR (extended support release) is a special version of Firefox designed for organizations and workplaces where they do not want so many updates so frequently and want to work with one version for a long time. Firefox ESR is not for individuals (home users) who want the latest technologies, newest features and performance enhancements as soon as they are rolled out. While Firefox ESR does not receive as many updates so frequently (only one ESR version is released every year), it does not mean that it is insecure – it does receive all the security related updates as soon as they are available. But the latest features that come with the regular release of Firefox appear only after 5-6 updates later in Firefox ESR.
So how do you get Firefox ESR for your computer? You can either visit the Firefox ESR website at https://www.mozilla.org/en-US/firefox/organizations/ or you can access Mozilla FTP at https://ftp.mozilla.org/pub/firefox/releases/ and look for the ESR versions. The ESR versions also follow the same version numbering system as the regular releases, only an extra ESR is appended after the version number. For example, at the present time the latest version of Firefox ESR is 52.2.0 ESR.
Summary: Firefox ESR stands for extended support release version of Firefox. A new version of Firefox ESR is released only once a year, but security updates are released as soon as possible. It is ideal for people who do not want new versions of Firefox updated every few weeks.