Prototyping is an approach used in evolutionary system development. In this book, the authors show which forms of prototyping can be employed to tackle which problems. They take a look at the tools used in everyday software development with a view to determining their suitability for prototyping, and attempt to elucidate prototyping as a methodological concept. Part I of the book looks at prototyping as an approach for constructing and evaluating models. Traditional approaches and phase-oriented life cycle plans are discussed. Prototyping overcomes fundamental problems associated with life cycle plans. The authors present their own concept of evolutionary system development. Part II shows to what extent technical support of evolutionary system development is possible. Various tools for supporting prototyping are discussed and prospective trends are indicated. Criteria are listed to help the reader choose between the various development environments currently available or likely to become available in the near future. Case studies are used to illustrate how prototype construction can be integrated in software projects.