1) Separating normal code from exception handling code to avoid abnormal 
termination of program.
2) Categorizing in to different types of Exceptions so that rather than 
handling all exceptions with Exception root class we can handle with specific 
exceptions. It is recommended to handle exceptions with specific Exception 
instead of handling with Exception root class.
3) Call stack mechanism : If a method throws an exception and it is not handled 
immediately, then that exception is propagated or thrown to the caller of that 
method. This propogation continues till it finds an appropriate exception 
handler,if it finds handler it would be handled otherwise program terminates
abruptly.