Many have heard about but didn’t try do it, other don’t know what is it, other have did it but doesn’t know all possible features.

The rooting of an Android device allows to obtain full privileges (administrator) on the device. The main advantage is to have a full control of the device, but it can be also a disadvantage if you don’t pay attention (an extreme example is to delete all the content, including system files).
The root is an operation that includes some risks (brick of the device if something goes bad) and generally is not covered by official warranty.
Not all smartphone models can be rooted, how to know it? You can do a simple Google search “root + model” to look if there is something. Moreover you must find the right guide because the root procedure is not universal but change by phone model. The starting point is the famous XDA Developers web site, a forum created and mantained by amateur/indipendent developers and fans. You can also see on web sites rooting process cited as modding.

Once root is done a user can:

- install a customized ROM
- install programs that requires root privileges

Install a customized ROM
A customized ROM is a stand-alone version of operating system, including kernel, applications, services. As the OS from Google is open source, the developers can take the stock ROM and modify them. These custom ROMs generally are used for 2 reasons: improve phone performances (optimize/speed the system), update Android version even if officially not available from the brand.
And if you encounter problems or don’t like a ROM you can simply change it and install another one.

Apps that requires root privileges
these programs using root privileges allows to do some tasks that normally are not available. Most used are ROM Manager, ROM Toolbox, Titanium Backup, Root Explorer, Wireless Tether, Chainfire 3D, SetCPU