TWRP recovery let’s you do a number of cool stuff but the whole point of having a custom recovery is to be able to flash unsigned .zip files. These .zip files could be anything from a custom kernel, boot, recovery, MODs or full custom ROMs.
What is a Custom ROM ?
One of the best things about the openness of the Android platform is that if you're unhappy with the stock OS, you can install one of many modified versions of Android (called ROMs) on your device. A new ROM can bring you the latest version of Android before your manufacturer does, or it can replace your manufacturer-modded version of Android with a clean, stock version. Or, it can take your existing version and just beef it up with awesome new features—it's up to you.
How to Install A Custom Rom Using TWRP Recovery
Let's get's started... before we begin make sure you have TWRP recovery installed
Step 1 : First switch off your smartphone then Boot into Recovery mode
- For Samsung Galaxy devices : Press and hold Volume Up+Home+Power for 5 seconds
- HTC/Nexus devices: Press and hold Volume Down+Power buttons then select recovery).
- If you have another device,try googling on how to enter recovery mode.
Step 2 : In Recovery mode you will see option like this, Backup Your Current Rom by tapping on Backup
Step 3 : You need to Wipe your device by factory Reset
Now you are ready to install new Custom Rom on your Android
Step 4 : Go back and Tap on Install and choose the Rom zip you want to flash
Note : If you are installing an AOSP ROM like LineageOs, Resurrection Remix, repeat this step to flash Gapps zip file. Otherwise go to next step.
Step 5 : Reboot and you should see your new ROM (Be patient first bootup will take 5-10 min)
That’s all. Your device will now reboot with the Custom ROM you just flashed. Since this will be the first reboot after flashing a new ROM, it might take some time to rebuild cache and finish boot, have patience. If you have any questions or queries then drop a comment in comment box