What is and difference between Stock ROM and Custom ROM

A device's firmware or official ROM is usually of two varieties: Google's Android operating system commonly referred to as Stock ROM and a custom operating system referred to as custom firmware or Custom ROM. Only a few select devices come with the original Android OS, such as Google phones and some Nokia phones, Xiaomi Mi A series phones, and more. In most cases, the phones ship with the manufacturer's branded firmware, such as OnePlus phones, Samsung phones, and more, called Custom ROMs.

Stock ROM

When you buy a brand new Android phone or Android tablet, the device comes with a stock ROM or Stock ROM. Here, ROM refers to the "firmware" of the device. The ROM is none other than the operating system of the device you are using. Stock ROM is the default ROM, i.e. the operating system, provided by the device manufacturer. Basically, a Stock ROM is the original or you can say, the official software designed by the original device manufacturer for that particular device. What is more, Stock ROM is software that runs on the mobile device which is stored in read-only memory. A true Stock ROM does not undergo any cosmetic / functional changes in its code by the device manufacturer, but it has its own unique features to attract customers.For example, Google's phones or other mobile devices are pre-installed with their own factory firmware, while other device manufacturers such as Samsung, Asus, Xiaomi, etc. they use their own original firmware to create a Stock Android Experience.

Custom ROM

Custom ROM or Custom ROM is a uniquely modified operating system developed and built by a third party vendor that is available for older or newer devices prior to the release of the manufacturer update. A custom ROM offers more refined and customized user controls and flexibility than the Stock ROM because the device is fully unlocked so that users can customize their device to their taste. A custom ROM replaces your device's original Android OS with a new version of the Android OS. However, replacing the stock ROM with a custom ROM may void your device warranty.

Difference between Stock ROM and Custom ROM

FIRMWARE

The ROM is nothing but the operating system of the mobile device. Stock ROM is the default ROM, i.e. the operating system, provided by the device manufacturer. ROM Stock is the official firmware from the device manufacturer that undergoes rigorous testing and scheduled release cycles. A custom ROM, on the other hand, is unofficial firmware for a specific device developed by some independent developers who have made some changes to the source code and released it to the general public. Custom ROM is uniquely modified firmware developed and built by a third party vendor.

STABILITY

ROM Stock is the original and official software designed by the device manufacturer for that particular device and which undergoes rigorous testing and scheduled release cycles to ensure the stability of the operating system. Custom ROMs, on the other hand, can be notoriously unstable because they are independently developed and tested at a much faster rate, and unscheduled release cycles mean there is no guarantee on operating system stability.

UPDATES

Since Stock ROMs are the official firmware released by the device manufacturer itself, users get automatic over-the-air updates and the installation and updates are done automatically by the manufacturers. However, manufacturers often stop releasing updates for older devices. Custom ROMs replace the device's original operating system with its own custom operating system, which requires a complicated installation process that requires rooting the phone, which could void the device's warranty. However, custom ROMs offer continuous updates for the device even after its production has been discontinued.

PERFORMANCE

Although the official firmware, which is the stock ROM, is more stable than a custom ROM, overclocking is not allowed and users often get limitations in device functionality based on region, carrier, etc. However, stock ROMs are designed to provide optimum performance due to their stable environment. Custom ROMs, on the other hand, allow for extensive customizations and all kinds of performance improvements, such as battery performance, new themes, new UI, and more.

Conclusions

Finally, we can conclude by saying that you may feel that rooting your phone and installing a custom ROM is the smartest thing to do as a custom ROM offers not only more flexibility but finer controls and allows for extensive customizations and all kinds of performance improvements. However, before you jailbreak your phone, remember that installing a custom ROM may void your mobile device's warranty. And unlike stock ROMs, custom ROMs can be notoriously unstable. However, custom ROMs are also being developed at a much faster rate, so updates reach end users regularly and much faster than stock ROMs.