Rooting an Android phone can unleash a whole new world of possibilities. The things you can do with a rooted phone that you cant do with an unrooted phone includes
- installing custom ROMS with the latest Android version and better performance
- use applications that require super user access
- APPS2SD. Install applications to an external SD card partition
- overclock your CPU and other hardware level tweaks
All that is just the tip of the ice berg. There are far too many applications that do the simplest yet the most useful of things that require a rooted phone to mention here. Rooting will not alter your phone in anyway. What it basically does is allow applications to use special permissions that are otherwise not available in unrooted phones. There will be no visual or performance change when you root a phone. If you have an HTC Android phone, just head over to the unrevoked website, chose your phone and follow the instructions.
For owners of other phones like Samsung or Sony Ericsson, head over to XDA to find out more information. There are roots available for almost all Android phones.