goal of system testing is to validate the software product 
against requirement specification.

this stage is intended to find the defects that can be 
exposed by testing the entire system.

a series of different tests each test having different 
purpose are done such that together and all system elements 
have been properly integrated or not.
 
it checks that the system performs all its functional 
requirements and it satisfying all its non-functinal 
requirements or not