This guide covers a rapid prototyping method for developing information systems that is particularly relevant to systems for the healthcare sector. Intended readers of this guide are people who develop information systems, and students and teachers of system development methods. Rapid prototyping is an approach to developing information systems which produce a working model more quickly than conventional approaches. Where conventional methods concentrate on preparing Requirements and design documents that describe the needed system, rapid prototyping methods concentrate on preparing a working prototype. Users and developers learn the functional requirements and an appropriate system design by interacting with a series of prototypes, each of which is rapidly produced from a starting framework or from an earlier version. A prototype can evolve into an operational system, it can serve as an exact behavioral specification of an operational system, or it can be used to explore the feasibility of a new idea or design which can be incorporated in a larger system. The method is rapid in preparing each version of the prototype, but the overall time required for system development may be more or less than the time required with conventional methods. Rapid prototyping is most appropriate when the Requirements or design for a system are not well understood, or when experimentation is required to explore some aspect of system behavior. It is not appropriate in hazardous settings, or when the requirements are well understood. The guide recommends use of prototyping tools, but it is not a standard for the tools themselves. It does not cover executable specification tools. Transforming a prototype that is used to clarify Requirements into an operational system is discussed briefly in Section 8 and in detail in other referenced standards . This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.