Rapid Prototyping is a software development technique, where prototypes of the final product are being produced throughout the development process. Instead of waiting until the complete product is finished, the client can see the prototypes throughout the designprocess. The design can be adapted to special client's whishes early on in the process and the development of the website can be followed.
It also makes it easier to place the new system in an organisation, because the people have already seen it. They may have even worked with one of the prototypes and been able to tell their own ideas about it and have them implemented in the system.