The Waterfall model is a software development process that follows a staged approach to producing a product. It was the first modern process model to be introduced and is also referred to as a linear-sequential life cycle model. It is a type of software development process that involves a cascading sequence of stages, each completed before the next one begins. In this model, progress flows quickly at the beginning and slows down toward completion.
The Waterfall Model was developed by Winston W. Royce in 1970 as a formal software development process, though it was not widely adopted at the time. Royce applied the traditional engineering model of a cascade to the entire development process. He believed that this model would allow for additional control and organization in the creation of software.
In the Waterfall Model, each stage builds upon the one that precedes it. Development begins with understanding the problem and creating the software specifications. The design phase follows, in which a plan is created for the code that will be written, along with user interface designs. After the code is written, it is tested in the coding-testing phase. Finally, the product is released to the public and maintenance and support is provided.
The Waterfall Model has been criticized as inflexible, as it does not permit any changes or alterations once a stage has been completed. It also assigns each stage its own time frame, making it difficult to incorporate changes late in the process. As a result, software development processes such as the spiral model and agile development have been developed as a result.
The waterfall model still finds some applications in software development, particularly in maintenance and support. It is also used in the manufacturing industry in which a product passes through a series of stages to be produced. The model has been described as a type of “industrial relic” and has been largely replaced by more agile development processes.
