What is phone rooting? What is a custom ROM?

If you've been searching for how to fix problems with your Android smartphone or tablet and come across words or phrases that you don't understand, like root, flash a custom ROM, unlock SIM or anything similar self, then this article is for you.

Android experts probably already know what these terms mean, so here's a beginner's guide looking to learn about all things Android-related.

What is phone rooting?

Rooting a phone means gaining access to system files on an Android device. By default, no Android device is rooted. So if you just bought an Android device and did nothing with it, chances are it's not rooted.

Manufacturers do this because giving every user root access leads to a lot of problems. Having root access allows you to access files on your device that - if deleted or edited in the wrong way - can damage the device.

But rooting a device allows you to make a lot of really cool changes if you know what you're doing, so a lot of people choose to root their devices. Note that rooting an Android phone will void its warranty.

The way you root your device will vary from model to model. For some devices, this can be a difficult process that involves circumventing the manufacturer's safety precautions. For others, things can be as simple as plugging your phone into your computer and pressing a button. You can always check out the XDA forums for instructions for your particular device.

https://forum.xda-developers.com/

Once your device is rooted, you won't notice any major changes right away. The joy comes from what you can do after the device is rooted. You can then use apps that require root access, flash custom ROMs, tweak certain aspects of your phone, etc.

For example, you can remove some bloatware without root, but to really get rid of it you need to root your device and use Titanium Backup or a root uninstaller.

What is Unlock?

Unlock is a confusing term because you can unlock many different things.

Unlock network/SIM

A network/SIM locked device is typically a device purchased from a service provider or to a specific service provider at a supported price. The carrier will then lock the phone so that you can only use it with them.

But if you pay for the phone and want to switch carriers, the carrier is required by law to provide you with an unlock code (at least in the US and EU), so you can just contact with your service provider for the code.

Sometimes, unlocking your device is more complicated than that.

What is phone rooting? What is a custom ROM? Picture 1

Unlock bootloader

Bootloader is a piece of software that runs every time you turn on your Android phone and it is usually locked by manufacturers. With the bootloader locked, you cannot root your device.

What is a custom ROM?

ROM stands for Read-Only Memory, but that name is now a bit misleading as it no longer has anything to do with this. ROM, at least in the Android world, is basically the software your device runs on.

So when you hold a Xiaomi smartphone, it looks and behaves differently than a Samsung smartphone. That's because both Xiaomi and Samsung take the original Android code, tweak it, and develop their own ROMs. Xiaomi's ROM is different from Samsung's ROM, although both are Android.

So a custom ROM is a ROM not built by the manufacturer but built by someone else. Sometimes it's just an indie programmer with some time and passion to make ROMs. In other cases, it's a larger group like LineageOS whose task is to create a certain type of ROM.

After rooting, you can flash a custom ROM. Flash, in this case, basically means load or install. Installing a custom ROM means that you are installing a new ROM on your device and completely erasing the old ROM.

When searching for custom ROMs for your device, there are several names that you may come across:

1. Pixel Experience: As the name suggests, has a similar ROM to Google's Pixel phones. This ROM is currently one of the most commonly used custom ROMs out there, and for good reasons.
2. LineageOS: LineageOS, formerly known as CyanogenMod, is one of the most popular custom ROMs you will come across. It offers a great feature set and was even considered a stock ROM for some manufacturers in the past.
3. AOSP: Android Open Source Project is the version of Android that Google makes available to the world, commonly known as stock Android. You may see people saying that their ROM is "AOSP based" or "stock Android based", that just means they took the AOSP code and changed it to their liking.
4. AOSIP: Android Open Source Illusion Project integrates features from various popular custom ROMs into AOSP ROMs.

But don't be afraid to try other named ROMs from lesser known sources. These are not the only reliable sources. They are just the most widely known.

Other useful Android terms

Custom recovery

If you enjoy tinkering with your Android device, it may take a long time to recover. That's where you can flash ROMs, backup and do the heavy lifting.

However, a stock restore on your device can't do any of that work, so you need a custom one. TWRP is a custom recovery for installing custom ROMs. TWRP stands for Team Win Recovery Project.

Nandroid Backup

Of course, there are ways to backup your Android device without rooting it, but a Nandroid backup is a complete backup. It basically makes a full copy of everything on your device and saves it. That way, if you run into any problems (since you have root access and it's possible), you can simply flash your Nandroid backup and roll it back to the original location.

The name Nandroid is just NAND (a type of flash memory) and Android combined.

Kernel

The kernel is like the operating system's engine - you don't really see it, but it's in the background doing all the hard work.

If you want, you can flash a custom kernel. Sometimes these kernels are optimized for performance or battery life - sometimes, they're just needed for some features to work properly. Either way, you should be fine sticking with your stock kernel unless you really want to change it.

Brick

Brick your phone basically ruin it. If your phone doesn't work anymore, you've made it 'brick'. This is usually a phrase you won't be happy to come across.

Soft brick usually means the device is still repairable. Maybe you're stuck in a bootloop (your phone keeps rebooting) or you booted the device up but it only shows half the screen. That's usually something you can get out of pretty easily.

Hard brick on the contrary is quite serious. You've had a problem with something on the system level that can't be fixed and your device isn't working. This is a rare occurrence, but it can happen and you will see warnings everywhere that no one but yourself is responsible for your device being bricked.

Anyone looking to tinker with their Android device should visit the XDA forums and take a look at their specific device. Everything you need will be tailored to your particular device and possibly even the carrier version of that device.

There are downsides. Some apps won't work if they feel that your device is rooted and you could damage your phone if you're not careful. But this might be totally worth it. Having a rooted device gives you complete freedom to tweak how it works, and the process of rooting and flashing ROMs can be a lot of fun at times.

Micah Soto

Update 24 May 2022