Rapid Application Development is a software development methodology, which involves iterative development and the construction of prototypes. It is a merger of various structured techniques, especially data driven Information Engineering with prototyping techniques to accelerate software systems development.
RAD calls for the interactive use of structured techniques and prototyping to define user's requirements and design the final system. Using structured techniques, the developer first builds preliminary data models and business process models of the business requirements. Prototyping then helps the analyst and users to verify those requirements and to formally refine the data and process models. The cycle of models, then prototypes, then models, then prototypes and so forth on, ultimately results in a combined business requirements and technical design statement to be used for constructing new systems.
RAD approaches may entail compromises in functionality and performance in exchange for enabling faster development and facilitating application maintenance.