Understanding Custom ROM
Sometimes you might wonder how does a Android OS functions and whats behind that and somehow can you customise it beyond substratum themes, launcher, icon packs, fonts and push your own taste in your phone with extra features and sometimes the Android Version Upgrade for a device which might be left behind by OEM.
If you tried searching on internet you might come across the terminologies like AOSP, Custom Roms, Lineage OS, And would wonder what these things are and how you can use them.
So the base here is just AOSP (Android Open Source Project), Its codebase that has been opensourced by several developers and successfully supported by google since a decade now. But to be more specific regarding open-source codebase, You can basically modify it anyway you want so developers thought how about making our own fork of AOSP and adding desired things into it and this is what Custom Rom is all about.Source Developers fork codebase of AOSP and modify the design, performance and Device Developers make kernel modifications and device tweaks to give better performance then so called Stock Rom.
So the MIUI, FlymeOS, ColorOS, OneUI are some of the common Stock OEMS by vendors like Xiaomi, Meizu, OPPO and Samsung. The better replacement can be a Custom Rom cause it has less bloats or heavy apps(the prebuilt apps of oems are heavy) and using opensource applications of google or aosp on devices to give better battery life, performance and consistent updates even after the vendor has put EOL(End of line) over the updates.
Few examples of major Custom Rom projects are LineageOS, AICP Rom, Resurrection Remix, Pixel Experience which are independent organisations making Custom OS source since quite a while now, and they do that with FOSS things i.e no one needs to pay anything in order to use them. You can read more about these projects at XDA Developers.
Using a custom roms require a Unlocked Bootloader, so you can understand bootloader as bootloader is a vendor-proprietary image responsible for bringing up the kernel on a device. It guards the device state and is responsible for initializing the Trusted Execution Environment and binding its root of trust. By default its locked by mobile-phone supplier and to replace proprietary OS and Kernel it needs to be unlocked.
Unlocking guides can be found : Xiaomi, Samsung, Realme
Now once you have unlocked your device, you are free to use a Custom Rom, but in order to flash it you need a Custom Recovery. So basically custom recovery is a third-party recovery environment. Flashing this recovery environment onto your device replaces the default, stock recovery environment with a third-party, customized recovery environment. Major recovery projects are OrangeFox, TWRP, Redwolf , One can visit there website and check support for there device and flash it with ease, You can use Flashify or terminal to flash a recovery.
After installing a custom recovery you must need to check websites of major custom rom projects and check if they support your device uptill now or not, You can also use XDAForums or Telegram for unofficial support for some devices. Every custom rom comes with different styles, customisations and features which are special in there own way. Flashing custom roms is easy and nothing too developer knowledge is required, one can easily get used to it and existing users can reportedly observe their devices feeling more snappy then early by the modifications development teams makes in source.
You can undoubtedly switch to using custom roms as they are regularly updated with googles security patches and CAF/Qcom Tags plus they add a new life to your old smartphone, and can at some extent boost its performance and battery life.
