Android ROMs

An Android ROM is the Operating System of an Android device and is based on the Android source code.

What are Android ROMs?

ROM is the part of a device's memory that cannot be directly edited by a user. An Android ROM is the OS of an Android device and is based on the Android source code which is edited to support hardware and add more features. A stock ROM is one which comes pre-installed with a device whereas a custom ROM has to be installed manually. A custom ROM provides many features but generally voids a device's warranty. The requirement and installation of custom ROMs has declined due to the following reasons:
The end on Cyanogenmod
Reduced reasons for installing custom ROMs
Installing ROMs is more difficult

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ROM stands for Read Only Memory, it is the part of the device's memory which contains the OS components and is not directly editable by a user. An Android ROM or is the firmware of a device based on the Android source code. It is basically the whole OS of an Android device. Android is an open-source platform that allows anyone to edit it's source code and distribute their creations.

OEMs selling Android phones create their own Android ROMs for their devices to make it compatible with their own hardware, add more features and change the look and feel of Android.

What are stock and custom ROMs?

A stock ROM is one that comes preloaded with a device. Whereas a custom ROM is one that can be flashed(installed) separately on a device(With a custom recovery, after rooting). These include Lineage OS(formerly Cyanogenmod), Paranoid Android, OmniROM and MIUI.

error_outline A custom ROM can be pre-installed as stock on a device. Most Xiaomi products have MIUI as stock ROM.

A custom ROM usually has more features and customisation options. Custom ROMs may also be based on newer Android versions which the OEM has decided not to provide to the device, in other words a custom ROM can provide extra Android updates to a device.

In addition to this, a custom ROM can overclock hardware to increase performance or it can underclock hardware to increase battery life. But installing a custom Rom on a device generally voids it's warranty.

Cyanogenmod and the deterioration of Android ROMs

The end of Cyanogenmod

Cyanogen Inc. was arguably the biggest organisation developing and investing in Android ROMs with Cyanogenmod(One of the best android ROMs). As Cyanogenmod was feature rich and open source, a lot of developers started making ROMs based on Cyanogenmod and not the Android source code.Cyanogenmod shut down in late 2016, even though it has been succeeded by Lineage OS, the number of developers is far less.

Reduced reasons for installing custom ROMs

Android Oreo

Over time the Android ecosystem has matured. OEMs have reduced bloatware, added a lot of features and have created cleaner UIs. OEMs are now providing more support and prolonged updates to their devices. Google's new Project Treble is also going to increase the time period for which devices get Android updates. Besides, installing a custom ROMs nowadays also means sacrificing security and sometimes camera quality.

Installing ROMs is more difficult

More devices are coming with permanently locked bootloaders, which means you can neither root your device nor install custom ROMs. OEMs and even Google discourages custom ROMs and thus any way to root and install a custom ROM is more risky and difficult.Thus, even developement and support of custom ROMs have reduced.

Custom ROMs have led to great features being incorporated in Android itself, but with lesser need and difficult installations, custom ROMs are slowly dying.