Software testing is the most important and time consuming part of software development life cycle, its purpose is to detect software failures so that defects may be recovered and corrected in early phase. Software testing is a process of confirming that the product/software that has been manufactured by programmers is a quality product and to assure that the manufactured product is working according to the specification and satisfying the customer needs. There are many approaches to software testing, but effective testing of complex product is essentially a process of investigation, not merely a matter of creating and following route procedure.