What is Waterfall Model

The waterfall model is a linear, sequential approach to the software development life cycle (SDLC) that is popular in software engineering and product development. The waterfall model emphasizes a logical progression of steps. Similar to the direction water flows over the edge of a cliff, distinct endpoints or goals are set for each phase of development and cannot be revisited after completion.

Waterfall Model is a sequential model that divides software development into pre-defined phases. Each phase must be completed before the next phase can begin with no overlap between the phases. Each phase is designed for performing specific activity during the SDLC phase. It was introduced in 1970 by Winston Royce.

Advantages of Waterfall Model

Before the next phase of development, each phase must be completed
Suited for smaller projects where requirements are well defined
They should perform quality assurance test (Verification and Validation) before completing each stage
Elaborate documentation is done at every phase of the software's development cycle
Project is completely dependent on project team with minimum client intervention
Any changes in software is made during the process of the development

Disadvantages of Spiral Model

Error can be fixed only during the phase
It is not desirable for complex project where requirement changes frequently
Testing period comes quite late in the developmental process
Documentation occupies a lot of time of developers and testers
Clients valuable feedback cannot be included with ongoing development phase
Small changes or errors that arise in the completed software may cause a lot of problems