What is the waterfall model? A waterfall model is a model that organizations use to help them complete their projects in a more organized and structured way, like a guide. The waterfall model has five phases that the organization must follow in order: requirements, design, implementation, verification and maintenance. The first phase (requirements) is when the organization needs to know what the requirements will be when creating the system, what they need and when they need it. During the design phase the organization should first draw some sketches of how the system should look, the interface and the DFD (data flow diagram). They would need to choose the final project so they can move on to the next phase, implementation. This is when you create the system, you use the design you created earlier to help you as a guide to complete this phase. The next stage is verification, which is to check whether the system you have created is suitable for the organization, is it reliable, is it easy to use, things like that. You can test the system by creating a survey to see if the system is good enough. The last phase is maintenance, this happens after publishing the system, you need to maintain it by making updates and fixing errors. Why do people use a waterfall model? Many organizations use a waterfall model because it will be easier for them to create their own system, the waterfall model is like a guide for them and shows them the stages they need to go through to create a good system. This will save a lot of time for the organization because they won't need to research what they should do next and how to do it, maybe they will skip a step and not even know... half of the paper......the advantage of the v-model is which is simple and easy to use and works very well with small projects. The downside is that it's not that flexible, meaning you can't modify it further. DFD (Data Flow Diagram) The system analyst will use a data flow diagram to design the system. The DFD shows how the system works and what processes it has, so for example a GP would have the patient as the entity and the process would be the application form. The advantage of DFD is that it makes it easier to understand the system by displaying a graphical view of it. You can see the boundaries of the system, what the communication and connections of the system are. The downside of DFD is that because there are different types of symbols that represent something, it may be difficult to figure out what it is if you don't know what the symbol means.