If you're using pc or mobile then you may probably know Firefox a popular and open source non profit browser build by mozilla 
corporation back in 23 sept, 2002 which is considered as best alternative to Google's chrome to surf Internet faster with security and privacy focused features.

Firefox is available to people way before Google's chrome released for WindowsXP in 2 Sept, 2009 that's why there is always big competition between Mozilla Firefox and Google chrome browser on desktop and mobile devices, eventhough chrome wins intems of downloads on play store but still there are millions of users who prefer Firefox over chrome.

Anyhow, Mozilla didn't want to end thier competition with only browsers so they even created a operating system named Firefox OS for smartphones, computers, tablets, smart TV's, dongals to compete with Google Android OS in Feb 21 2013 then later discontinued in sept 2016 and forked to form Kai OS.

Firefox OS is free and open source operating system designed by mozilla based on gecko rendering system of Firefox web browser and linux kernel, that's why Firefox OS feel like you're running apps on browser and in actual Firefox OS only install and run open web apps that are based on web technologies like HTML5 so you can't access them without internet connection anytime.

While, Android is full fledged free and source operating system based on Linux which has real apps and doesn't require internet connection every time to access apps including that Android OS feels real with many advanced features and millons of apps on play store so people preferred Android OS over Firefox OS.

Eventhough, Mozilla tried alot to make developers build web apps for Firefox OS but still they failed just like Microsoft and Nokia lumia smartphones as developers already committed to Android operating system due to low cost smartphones and  developer friendly process to create apps and push them on marketplace like play store with millons of apps and billons of downloads every day.

In sense, Firefox OS failed to beat Android OS even in 2013 as Android OS already has strong foundation laid down with many advanced features and over the time Google added alot of features to improve user interface and user experience of users on Android OS with regular monthly security patches and privacy focused features.

Google also introduced web apps on Android OS and later upgraded it to PWA aka progressive web app in 2015 which is now popular and supported by almost all 
desktop and mobile browsers except the desktop browser of Firefox, anyway with PWA in existence Android OS users don't need Firefox OS to experience web apps thus eventually majority of users doesn't even shown interest on Firefox OS.

So, eventually Mozilla discontinued Firefox OS as there is no big development of web apps from developers including that there are no buyers for Mozilla Firefox OS smartphones as most people sticked to either Android OS or iOS powered smartphones, here at the final days of Firefox OS they released Firefox OS 2.5 version which any Android OS user can install to experience Firefox OS without replacing software.

But, Firefox OS 2.5 didn't worked well and mozilla failed again as Firefox OS 2.5 is Android custom launcher that is actually operating system according to Mozilla Firefox with numerous bugs, so users of Android didn't like Firefox OS much as they get better and original operating system experience on Google's Android OS.

Fortunately, you can still install Firefox OS on your Android smartphones but make sure you have old smartphone with old software to experience Firefox OS as on new smartphone with big screen and latest software Firefox OS 2.5 doesn't seem to work, anyway if you're interested in Firefox OS 2.5 version then let's know more info to explore more.

• Mozilla Firefox OS official support •

• How to download Firefox OS 2.5 •

It is very easy to download Firefox OS 2.5 from these platforms for free.

• How to install Firefox OS 2.5 with key features with UI / UX Overview •

- Open and Set Firefox OS launcher then tap on CONTINUE

- That's it, now you can install and run open web apps on Firefox OS 2.5

Atlast, the only attraction of Mozilla Firefox OS is web apps with some security features which are already available on Android, iOS, Windows, Tizen, and other operating systems, so there is not much special or unique about Mozilla Firefox OS to compare with Google's Android OS,

Overall, Firefox OS feels light comes with vibrant intuitive interface that ensures user friendly experience, but on Android OS you will get way better user interface and user experience where you can install custom roms with custom skins to experience different softwares everyday which is not possible on Firefox OS.

Moreover, it is worth to mention as said earlier Firefox OS was forked to form Kai OS which is now become popular operating system for keypad phones when reliance partnered with Kai OS to install it on Jio 4G phones, but Kai OS can't be compared with Android OS as Kai OS don't work on smartphones.

Finally, Firefox OS is more like a custom launcher then operating system and it doesn't have potential and features to compete and become alternative to advanced operating system like Android, that's why Firefox OS failed to beat Android and other other mobile operating systems, what do you think? are you an existing user Firefox OS? If yes do say your experience in our comment section below, see ya :)