Description of the Phases of Waterfall Model

� Requirement Analysis and Definition- All possible requirements of the system to be developed are captured in this phase. Requirements are a set of functions and constraints that the end user (who will be using the system) expects from the system. The requirements are gathered from the end user at the start of the software development phase. These requirements are analyzed for their validity, and the possibility of incorporating the requirements in the system to be developed is also studied. Finally, a requirement specification document is created which serves the purpose of guideline for the next phase of the model. During this phase research is being conducted which includes brainstorming about the software, what it is going to be and what purpose is it going to fulfill.� System and Software Design- Before starting the actual coding phase, it is highly important to understand the requirements of the end user and also have an idea of how should the end product looks like. The requirement specifications from the first phase are studied in this phase and a system design is prepared. System design helps in specifying hardware and system requirements and also helps in defining the overall system architecture. The system design specifications serve as an input for the next phase of the model. If the first phase gets successfully completed and a well thought out plan for the software development has been laid then the next step involves formulating the basic design of the software on paper.

� Technical Design / Detail Design- After the basic design gets approved, then a more elaborated technical design can be planned. Here the functions of each of the part are decided and the engineering units are placed for example modules, programs etc.

� Implementation and Unit Testing-On receiving system design documents, the work is divided in modules/units and actual coding is started. The system is first developed in small programs called units, which are integrated in the next phase. Each unit is developed and tested for its functionality; this is referred to as unit testing. Unit testing mainly verifies if the modules/units meet their specifications. At this phase, the whole design and its construction is put under a test to check its functionality. If there are any errors then they will surface at this point of the process.� Integration and System Testing-As specified above, the system is first divided into units which are developed and tested for their functions. These units are integrated into a complete system during integration phase and tested to check if all modules/units coordinate with each other, and the system as a whole behaves as per the specifications. After successfully testing the software, it is delivered to the customer. in the phase of Integration, the company puts it in use after the system has been successfully tested.� Operations & Maintenance-This phase of the model is virtually a never-ending phase. Generally, problems with the system developed (which are not found during the development life cycle) come up after its practical use starts, so the issues related to the system are solved after deployment of the system. Not all the problems come into picture directly but they arise from time to time and need to be solved; hence this process is referred to as maintenance.Maintenance and management is needed to ensure that the system will continue to perform as desired.Through the above mentioned steps it is clearly shown that the Waterfall model was meant to function in a

systematic way that takes the production of the software from the basic step going downwards towards detailing just like a Waterfall which begins at the top of the cliff and goes downwards but not backwards.