Rapid application development is a set of guidelines designed to improve the process of developing software in certain situations. The "rapid" in the title refers to a focus on finishing prototypes and releases faster than other methods typically allow.
Most guidelines covering how rapid application development works focus on releasing early prototypes of the software. Guidelines also dictate that developers begin work quickly and avoid long design stages. As a result, rapid application development often works best when the final goals of the project are fairly clean and the project is unlikely to expand significantly in the future.
Unlike many program design processes, rapid application development often puts less of an emphasis on formalized communication between team members, although developers still need to communicate with each other. As a result, the process often works best with small teams and with projects that are fairly simple for each member to understand.
While rapid application development can lead to faster development, it also requires some sacrifice. Thorough communication and documentation make programs easier to maintain in the future, especially if those who maintain the program were not part of the team that originally released the program. In addition, programs developed using rapid application development guidelines may be built in a manner that makes them difficult to adjust for different goals in the future.