Android Rooting Terms You Should Know
Before we get started, I would like to explain a few terms because the terminology can get complicated and confusing. This will help you to understand other device specific guides. I’ll try to keep it short and not go into (technical) details
ART stands for Android Runtime and replaces the formerly used Dalvik cache. It was introduced in Android 4.4 and has completely taken over in Android 5.0. I don’t want to go too deep into technical differences, but ART is said to improve battery life and app performance, amongst others.
The Bootloader is your phone’s software foundation. It’s basically what runs before your operating system starts (like a PC’s BIOS). As many manufactures don’t want you to modify your phone’s OS, it needs to be unlocked before you are able to root your phone or install custom ROMs (explained later).
This is something you don’t want to happen to your Android device. Like the name already implies, a bricked phone (or tablet) can only be used as a paperweight or nice decoration for your apartment. Bricked devices are irreversibly damaged and won’t work anymore. This can, for instance, happen if damaged ROMs are installed or wrong firmwares are flashed. Always make sure to read instructions and verify checksums (a set of numbers that identify the file) to make sure nothing goes wrong. If you’re lucky and your device is only soft-bricked, meaning that it does not boot but still turns on, you might be able to get it back to life.
Android, being based on Linux/Unix, offers a limited amount of UNIX commands (which most users won’t need anyways). BusyBox will implement more commands that are necessary for some root apps to work properly.
A custom ROM is a modified version of the Android operating system. Tweaks, additional features, different themes or an enhanced performance are usually included. Custom ROMs also offer the possibility to use a newer, unreleased, version of Android on your phone that might usually not be available for your device because of restrictions from manufacturer or providers.
Dalvik is a virtual machine that processes Android app code. Consequently, it is responsible for translating app code into actions on your Android device.
Fastboot is a diagnostic- and engineering tool which offers you several features such as launching in recovery mode or flashing image files.
The kernel is the brain of your phone that controls how the system and hardware interact. It’s basically the lowest level of your operating system that manages memory and hardware.
NAND stands for “Negated AND” or “NOT AND” and describes the hard drive partition that stores all system relevant information like the bootloader, recovery mode or the kernel.
A NANDroid backup is a complete system backup of your Android device. This backup can be restored later and might save your phone after flashing a faulty ROM or theme.
The radio is responsible for sending and receiving voice and data. Using an optimized radio can improve your phone’s reception or increase battery life.
Recovery mode offers you the possibility to perform system-level tasks (like formatting, defragmenting, etc.), backing-up your devices or install custom ROMs. Android offers a limited stock recovery function. More sophisticated recoveries like ClockworkMod Recovery and TWRP Recovery offer additional features and are easier to use.
Rooting will give you full administrator access of your device. It might also void your warranty (depending on the device and your place of residence), so make sure to handle your device with care after rooting it. You are always able to revert this process by simply flashing a stock-ROM (the original ROM installed by your phone’s manufacturer). Doing this will also “restore” your warranty.
S-OFF means that the NAND partition of your Android device is unlocked. This mostly applies to HTC phones.
Rooting your phone will create a new “account” with complete administrative permissions. This superuser account is used by some apps and functions.
Xposed Framework is an app that can be installed on a rooted Android device which offers custom ROM like features on stock Android. It currently does not work on devices running Android 5.0 because it requires the Dalvik cache which has been replaced by ART.
How to Fully Backup Your Device Without Root
If your Android device is not rooted yet, you won’t be able to perform NANDroid backups. I wouldn’t suggest to root your tablet or phone without having a proper backup, because there is always a chance of error and you don’t want to brick your device.
Simple ADB Backup let’s you create a full backup of your device without root access and is the perfect solution for users without root access. The free program also offers a restore function and runs on Windows and Linux.
Read this for more information. Android Rom and rooting dictionary