Joint Application Development (JAD) is a development methodology system originally used for designing a computer-based system, but can be applied to any development process. It involves continuous interaction with the users and different designers of the system in development. JAD centers around a workshop session that is structured and focused. Participants of these sessions would typically include a facilitator, end users, developers, observers, mediators and experts. JAD allows for a faster development process and minimizes errors at the same time. JAD also improves the quality of the final product by focusing on the up-front portion of the development lifecycle, thus reducing the likelihood of errors that are expensive to correct later on.
The opposite of JAD is RAD (Rapid Application Development)