What is Waterfall Model in SDLC? Advantages and Disadvantages

What is The Waterfall Model?

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.

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Different Phases of Waterfall Model in Software Engineering

Following are the different Waterfall Model phases:

Different phases	Activities performed in each stage
Requirement Gathering stage	During this phase, detailed requirements of the software system to be developed are gathered from client
Design Stage	Plan the programming language, for Example Java, PHP, .net or database like Oracle, MySQL, etc. Or other high-level technical details of the project
Built Stage	After design stage, it is built stage, that is nothing but coding the software
Test Stage	In this phase, you test the software to verify that it is built as per the specifications given by the client.
Deployment stage	Deploy the application in the respective environment
Maintenance stage	Once your system is ready to use, you may later require change the code as per customer request

When to use SDLC Waterfall Model?

Waterfall Methodology can be used when:

Requirements are not changing frequently
Application is not complicated and big
Project is short
Requirement is clear
Environment is stable
Technology and tools used are not dynamic and is stable
Resources are available and trained

Advantages and Disadvantages of Waterfall Model

Here are the popular advantages of Waterfall model in Software Engineering with some disadvantages:

Advantages	Dis-Advantages
Before the next phase of development, each phase must be completed	Error can be fixed only during the phase
Suited for smaller projects where requirements are well defined	It is not desirable for complex project where requirement changes frequently
They should perform quality assurance test (Verification and Validation) before completing each stage	Testing period comes quite late in the developmental process
Elaborate documentation is done at every phase of the software’s development cycle	Documentation occupies a lot of time of developers and testers
Project is completely dependent on project team with minimum client intervention	Clients valuable feedback cannot be included with ongoing development phase
Any changes in software is made during the process of the development	Small changes or errors that arise in the completed software may cause a lot of problems