Difference between Incremental Model and WaterFall Model

The Waterfall model and the Incremental Model are widely used in software development. The objective of having these models is to ensure that the software is developed in a systematic, organized and efficient manner. Read this article to find out more about the Waterfall model and the Incremental model and how they are different from each other.

What is the Incremental Model?

The incremental Model is a software development model in which the entire model is divided into various sub−development phases where the corresponding testing phase for each development phase is practiced. The execution of the phases, i.e., development and testing happen in a sequential manner, hence the model is sequential/parallel in nature. Since the sequential phases need to be functional, the cost of development is higher as compared to that of the Waterfall Model.

The complexity of the incremental model is higher than the waterfall model. The probability of the total number of defects in the development of an application is low, because testing is done in parallel to the development of the application.

The incremental model of software development involves breaking a project down into smaller parts, known as "increments", which can be easily managed. Each "increment" builds on the previous one, adding new functionality and features until the final product is complete. It provides more flexibility because the updates can be easily incorporated into the development process.

What is Waterfall Model?

Waterfall Model is the classical model of software development where each phase of application development is completed in a linear fashion. In the Waterfall Model, the complete process is divided into several phases and the process follows a linear and sequential approach, with each phase of the project being completed before moving on to the next phase. Testing is done at end phase of the development. The waterfall model is also known as the classical model or the traditional model. It is generally not regarded as a suitable model to handle large projects.

The phases of the waterfall model typically include requirements gathering and analysis, design, implementation, testing, deployment, and maintenance. This model is called "waterfall" because each phase flows naturally into the next, like a waterfall. One of the main advantages of the waterfall model is that it allows for clear and concise communication among team members, as each phase has well−defined goals and deliverables. However, it can be inflexible and does not allow for changes to be easily incorporated once a phase has been completed.

Difference between Incremental Model and Waterfall Model

The following table highlights how the Incremental model of software development is different from the Waterfall model−

Key	Incremental Model	Waterfall Model
Definition	It is the development model in which the entire model is divided into various sub development phase where corresponding testing phase for each development phase is practices. For every stage in the development cycle, there is an associated testing phase and the corresponding testing phase of the development phase is planned in parallel.	Waterfall model there is first development of the application and after which the different testing of application takes place. The complete process is divided into several phases, and each phase flows into the next, after its completion. Testing is done at the end of the development.
Type/Nature	The execution of the phases, i.e., development and testing takes place in a sequential manner, so the process is sequential/parallel in nature.	It is a relatively linear sequential design approach, as each phase should be completed in order to reach the next phase. So, the type of this model is Continuous in nature.
Testing and Validation	Each development phase is followed by its own testing. If any validation requires to be implemented, then it could be implemented at that phase.	Testing is carried out after the development is completed. Hence, if any missing validation is identified to be implemented, then that phase of development needs to be recognized and then that validation gets implemented.
Cost and Complexity	As sequential phases need to be functional, hence the cost is higher as compared to that of the Waterfall Model. Also, the complexity is more than the Waterfall model.	Due to linear development, only one phase of development is operational and hence the cost and complexity is low as compared to that of Incremental Model.
Defects	The probability of the total number of defects in the development of application is low as testing is done in parallel to the development.	The probability of total number of defects in the development of application is high as testing is done post development.

Conclusion

The most significant difference that you should note here is that the entire development phase in an Incremental Model is divided into several subdevelopment phases with their corresponding testing phases; whereas the Waterfall Model is one where each phase, after its completion, flows into the next and the entire testing part is left to be done at the end of the development.