Over the last few decades there has been a tremendous growth in information technology and its impact on everyday life. Complex software systems have become criticalto the operation of many systems in areas such as banking, communications, manufacturing,power generation, and transportation. Progress in computer science and accumulated experience with industrial production of software have led to the emergence of software engineering as a separate discipline. The software engineering discipline has been defined as"the application of systematic, disciplined, quantifiable approaches to the development,operation, and maintenance of software. " that is, the application of engineering to software.