A story board is a technique used to walk through typical scenarios before the application is built. It could consist of rough, hand-drawn, overheads used in a presentation to the team building the requirement document, including end users. The typical scenarios of the system are walked through in this draft fashion. Often, significant errors can be caught and prevented before they propagate into other phases of the project. The story board might be a GUI-only version of the application where pictures of the screens are presented. These GUI-only screens have no underlying application code but given an idea of what the end-user might see and feel while running the application. The GUI builder in NextStep is a good example of a tool that generates high quality story boards of an application complete with limited functionality and application stubs. In this case, if the story board is acceptable, then the application stubs can be implemented.