Rooting is a process allowing users of smartphones, tablets, and other devices running the Android operating system to attain privileged control (known as “root access”) within Android’s subsystem. Rooting is often performed with the goal of overcoming limitations that carriers and hardware manufacturers put on some devices, resulting in the ability to alter or replace system applications and settings, run specialized apps that require administrator-level permissions, or perform other operations that are otherwise inaccessible to a normal Android user. Rooting is analogous to jailbreaking devices running the Apple iOS operating system or the Sony PlayStation 3. On Android, rooting can also facilitate the complete removal and replacement of the device’s operating system.
Why Should You Root Your Device?
Rooting has lot of advantages.
1.Full control over your system
2.Ability to alter system files. You can replace many parts of the “Android Core” with this including:
-Core apps (maps, calendar, clock etc)
-Toolbox (linux binary that lets you execute simple linux commands like “ls”) can be replaced with Busybox (slightly better option)
-Add linux binaries
3.Run special apps that need more control over the system
-SuperUser (lets you approve or deny the use of root access to any program)
-Task Manager For Root (Lets you kill apps that you otherwise could not kill)
-Tether apps (like the one found at [android-wifi-tether.googlecode.com])
4.Backup your system
-You can make a folder on your sdcard and backup all of your .apk files to your sdcard (helps if an author decides to “upgrade” you to a version that requires you to pay to use the version you just had)
5.Relocate your (browser/maps/market) cache to your /sdcard
6.Relocate your installed applications to your /sdcard
7.Reboot your phone from the terminal app easily (su <enter> reboot <enter>)
Why Should You Not Root Your Device?
There are not many reasons for you not to root your device except the fact that your device’s warranty gets void. Usually all manufacturers provide a warranty of one year for the devices and they do not allow one to root the device and access system files. However, Android is an open source OS and hence there exists rooting! Also, you can unroot it later in case you wish to make use of your device’s warranty.
-The ability to accept OTA updates (well, you can but you would lose root, so its been made so they get denied)
-The sense that someone else controls your phone
-The need to sit in an Android chat channel asking how to get root
-The need for a stupid useless “File Manager” that lets you see filenames but almost nothing else.
-The ability to have a knowledgeable conversation with a T-Mobile rep about your phone. (Ask one of them to spell root for you)
Source : Root