The root user has super-user privileges on the system and is able to do practically anything and more or less make any changes he or she likes. In short, it allows you to do a number of things that is beyond the reach of ordinary users. Benefits of rooting may range from the ability to fully customize your device, add features, work around limitations, or even fix existing bugs or issues in the system.
- Apps and data backup - This allows you to backup every app on your device, including the data that the app uses. Generally, you need root access to do this because by default, each app only has restricted access to its own data, and by all rights should usually not be allowed to access or mess with other apps. One of the best backup tools available on Android is Titanium Backup Pro which naturally, requires root access to work.
- System image backup - This allows you to make a backup image of the entire Android system, including the bootloader, firmware and all installed system apps. This is in case a custom firmware installation goes wrong, or if some app misbehaves in an inexplicable way and you need a way to revert to a working copy. It's something like what Norton Ghost or Acronis Trueimage do for Windows PC's. The usual method to accomplish is this via CWM Recovery (also known as ClockWorkMod Recovery), but do note that the installation method is very much device-specific and varies between different models, and even between 3G and Wifi-only models. The root and CWM Recovery installation process for the Samsung Galaxy Tab 7.7 has been described in an earlier post here.
- Worldwide navigation - the default Google Maps bundled with most Android devices only has turn-by-turn voice-guided navigation enabled for a handful of countries, such as the US and Canada, and some European countries such as France, Germany, Italy, Switzerland and the UK. Outside of these countries, such as most of the Asian region, users who wish to have this feature need to use a modified version of Google Maps that has worldwide navigation enabled. Root access is required to uninstall the bundled Maps app before installing the modified version.
- SDcard write problem fix - some apps, in particular file managers and compression utilities, have write problems with micro-SD cards in Honeycomb tablets. This is related to a permissions issue and is described in further detail here. As system files need to be modified, root acess is required to fix this issue.
- Support for large files - if you need to copy large files like movies and such into your SDcard, you may encounter limitations since by default SDcards are formatted with the FAT32 filesystem which restricts file sizes to below 4GB. To be able to utilize files larger than that, you will need to format the SDcard to NTFS and install Drive Mount, which is able to mount NTFS volumes, with an option to auto-mount upon bootup.
- On-the-fly file encryption - the more security-minded amongst us know to secure our data with file encryption, and that truly transparent, real-time, on-the-fly encryption (OTFE) is one of the better ways to achieve that (as opposed to single file encryption which is slower and not as secure). The reference software for this in the Windows domain is Truecrypt, and the closest implementation so far in the Android world is LUKS Manager, which provides OTFE capability using AES encryption.
- Running Tegra 3D games - if you are into 3D gaming on Android you might have run into the fragmentation issue : some games are available only on certain models of phones or tablets that have a certain graphics chipset. Most commonly encountered are the cases where the games are built for the Nvidia Tegra chipset and the user has a Galaxy series device which uses the Mali chipset instead. This is where Chainfire 3D comes to the rescue, acting as a proxy between the gaming app and the hardware, translating OpenGL calls for the Tegra chipset into equivalent instructions for the Mali chipset. Root access is required because this involves low-level system function calls.
- Remove status bar on Honeycomb tablets - instead of hard buttons, Android tablets running Honeycomb nowadays have soft buttons on an always-present status bar at the bottom of the screen. And then there are some people who are distracted by it, say, when watching movies, and wish to remove even that entirely. This can be done via the Honeybar app.
- Alternative system fonts - one thing that those who wish to really customize their devices can do is to change their system fonts. The Root System Font Installer app lets users choose from over 200 system fonts, which together with custom homescreens and widgets, will enable you to put together a truly unique look for your device.
- User profile switching - one of the bugbears facing some Android users is that there is no obvious built-in way to switch between different user accounts and profiles, the way Windows users are simply able to do at the click of a button. This shouldn't be the case as Android is built upon Linux which *is* a multi-user operating system. The SwitchMe Root Profile Manager app takes care of this little shortcoming.
- Your device may be bricked if something goes wrong during the rooting process. There are 2 main types of bricking. A soft brick can still be recoverable by re-installing a fresh copy of the original firmware. A hard brick is a bit more tricky to deal with, requiring either a special "USB jig" to reset it - or a visit to the service center, which brings us to the second point.
- There is a risk that you may void your warranty if you have rooted your device, and then you subsequently encounter some problem, and bring it over to the service center for repairs. Of course for devices over the warranty period this is a moot point, and there have been a number of cases where rooted devices are still being accepted for warranty repairs, but for some this could be a serious consideration.
- The automatic updates provided by the PC-side software such as Samsung Kies typically check for the signatures of the installed kernels and ROM's, and on rooted devices, these software may block automatic updates of new firmware revisions. This may be a consideration for those who wish to have a seamless upgrade experience. For those who regularly dabble with Odin or Mobile Odin, CWM Recovery and such, it probably isn't that much of an impediment to download and install the updated firmware manually.
- If all you want to do is to install apps outside the Android Market (or known as Google Play Store nowadays), you do not need to root your device. All you have to do is to go to Settings, Applications, and check the "Unknown sources" box. That's it. There is no need to root an Android phone or tablet to install apps from alternative sources, unlike Apple's iPhone and iPad where you need to jailbreak the iOS device just to have this capability.
So these are the top 10 reasons to root your Android device, and 4 reasons to perhaps not to.
As for the actual mechanics of rooting the device, the instructions for each specific model of mobile phone or tablet are slightly different. For detailed instructions, you can head over to the XDA Developers forums and look for your model. In particular, the instructions for the Samsung Galaxy S2 are as described in this thread, and the Samsung Galaxy Tab 7.7 rooting instructions have been posted here earlier.