Root, as the name, suggests it is the deepest part of any electronic device.
As in case of plants the roots are the main part for them so in the case of electronics.
Root access is primarily not available to a normal user, which limits them in the number of functionality offered to them.
By rooting we means that gaining root access and modifying the system as per our need.
Rooting provides us a number of functionalities like over clocking, down clocking, performance enhancing etc.
Rooting might be looking cool to do but one limitation of it is that if something wrong happens to your device the manufacturer holds the right to deny the warranty and may not provide you with their assistance.
Rooting also may your device vulnerable to many threats out there in the world like malware and ransomware etc it is so because the path to the root (main system) is locked by the vendor but you have opened the door for these threats to enter to your main system.