The high cost of software development personnel and the high rate of system failure has resulted in a rapid expansion in Rapid Prototyping and Rapid Application Development (RAD). With the premise that a successful complex system can only be achieved if there is a working simple system, this study demonstrates how the prototyping process fits into an evolutionary software development process. The book focuses on the growth of flexible, living computer systems demanded by today's users, rather than the old method of software development without the user in mind. It provides a practical approach with many illustrated examples.