How To Root Android Phone:

 

Root:

 Rooting is like getting supreme rights to your device so that some real changes can be made to your Android device. However, through rooting you are give the freedom to make drastic changes to your device and you can also use third party applications, alter system files, install apps directly to the SD card, use different android version, improve performance, enable
Wi-Fi and bluetooth tethering and so much more. 
 Some Android devices have problems with installing application, this is because their internal memory is too low. Rooting can solve this issue by downloading and installing apps using your SD card's memory only.

Rooting Process: 

 Make sure you have the appropriate data cable, and have made a back up of your device. Search for rooting software on internet and install to them. Some of these rooting software may need the android software developer kit (SKD). You will need to enable USB debugging mode on your android device. To do this setting> application> development, and check the usb debugging option.
 Now make sure your phone is connected to the computer, your running the SKD application, and the rooting software.

Rooting Your Device:

 The rooting procedure varies from device to device. Not all device use the same rooting software, and in addition, every device has their own custom ROMs. You cannot install a custom ROM developed for Galaxy S3 on a Galaxy Nexus. 

DrawBack: 

 Of course, all the benefits are not without risk. Firstly you will be voiding your warranty and secondly, you might end up "Bricking you device". you will only cause irreversible damage however, if you mess up big time during the whole rooting procedure. If the instructions are followed step by step, then there should be no problem.