What is the V Model in Software Development?

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Relia Software

Software Development

The V Model, the Verification and Validation Model, is an SDLC approach that prioritizes early and rigorous testing throughout the development process.

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Software engineering is rapidly expanding thanks to the availability of viable software development models. The V Model in software engineering is a prominent software development lifecycle model (SDLC) that involves sequential execution and parallel testing for each step of development.

This article discusses the definition and differences between the verification and validation phases of the V Model, its principles, pros and cons, and where this model is best and where it should be avoided. Let's check it out!

What is the V Model?

The V Model, or the Verification and Validation Model, is an SDLC approach that prioritizes early and rigorous testing throughout the development process. Its name is derived from the V-shaped visual representation, in which the development phases on the left (verification) mirror the corresponding testing phases on the right (validation).

The V Model divides software development into design, implementation, integration, and qualification testing. This systematic strategy ensures that each development stage has a clear testing equivalent, producing high-quality software.

Testing can begin earlier with the V-model's processes for minor software development increments. Early bug detection speeds up development, reduces costs, and improves quality. Continuous integration and deployment fit well with the approach.

what is v model
What is the V Model? (Source: Internet)

2 Phases of the V Model

The V Model establishes a clear path, with each stage in development having a specific testing equivalent. It has two main phases which are verification and validation. Development begins with design at the top-left end of the verification model, proceeds through implementation at the bottom, and culminates with final testing at the validation upper right.

Verification Phases 

The verification phase checks the product development process to ensure the team meets the criteria. Verification involves 5 steps that are business requirement analysis, system analysis, software architecture design, module design, and coding.

  • Business requirement analysis: Business requirement analysis helps the team understand customer product requirements. 

  • System analysis: System engineers will use the user requirements document to analyze and interpret the proposed system's business requirements.

  • Software architecture design: The team chooses the software architecture based on the list of modules, their brief functionality, interface relationships, dependencies, database tables, architectural diagrams, technological information, and more during software architecture design. This phase creates the integration testing model.

  • Module design: The development team divides the system into tiny modules and specifies their low-level designs during module design. 

  • Coding: The development team chooses a programming language depending on design and product needs. Coding standards and procedures are in place, and the code will be thoroughly reviewed to ensure performance.

Validation Phases 

The validation step uses dynamic analysis and testing to guarantee the program satisfies customer needs. This phase including comprises unit, integration, system, and acceptability testing.

  • Comprising unit: The team creates and runs unit test plans to find code or unit issues. Program modules are tested to ensure they work properly when isolated from the rest of the code.

  • Integration: Integration testing verifies that groups formed and tested independently may coexist and interact by performing integration test plans developed during architectural design.

  • System testing: System test plans created by the client's business team during system design are executed during system testing. System testing ensures the team meets application developer objectives.

  • Acceptability testing: Based on the business requirement analysis element of the V-model, acceptance testing entails evaluating the software product in the user environment to find compatibility concerns with other systems. In the real user environment, acceptance testing finds non-functional concerns like load and performance faults.

Principles of the V Model

The V Model emphasizes testing and quality assurance throughout the development process. Here are some of the V Model's core principles.

Integrate Testing Throughout Development. 

Testing is more than just a final step in the development process. Instead, testing is incorporated throughout the development process, from requirement gathering to deployment.

Plan Testing in parallel with Development

Each level of the development process has its testing phase. Testing efforts are planned concurrently with development activities to ensure that sufficient resources are available to support testing.

Prevent Defects 

The V Model emphasizes the necessity of preventing problems rather than simply detecting and correcting them once they have been detected. 

Develop Clear and Concise Requirements

The V Model lays a strong emphasis on precise and concise needs. Without a clear grasp of what the product is supposed to perform, it is impossible to write effective tests or create high-quality code.

Combine Development and Testing

In the V Model, development and testing are not distinct processes. Instead, they are tightly interwoven, and collaboration between developers and testers is vital to ensure that the program fulfills the necessary quality requirements.

Pros and Cons of The V Model


Due to the definition and principles of the V Model, this model has significant advantages.

Better Software Quality

The V Model's emphasis on early and ongoing testing is a major benefit. Testing throughout the development lifecycle finds and fixes bugs early. This preventative strategy reduces the chance of difficulties growing during development. Early detection and correction improve software quality.

Lower Defects

Each development process has a testing counterpart to ensure no stage is skipped. This rigorous testing helps developers find and fix bugs early in the cycle before they become more complicated and expensive. The V Model controls project costs and reduces rework by identifying and fixing issues early.

Improved Project Management

The V Model's stages and structure guide project management. Deliverables and testing activities for each phase simplify planning and resource allocation. Teams can better predict timelines, allocate tasks, and track progress. Developers, testers, and stakeholders communicate and collaborate better with this structured approach, improving project management.

Clear Documentation

The V Model emphasizes extensive documentation throughout development.  System designs, requirements, and test cases are well-defined. This extensive documentation has several uses. It assures project participants comprehend the system's functions. Additionally, excellent documentation helps engineers understand the system and make changes faster for future maintenance and updates.


The V Model has advantages, but it also has drawbacks. The drawbacks include:

Lack of Flexibility

The V Model's structure and sequentialness might be a drawback. The stiff framework may not suit projects with changing needs. The V Model's inflexibility can make it difficult to modify if project requirements change dramatically during development. Frequent modifications may require retesting and revisiting prior steps, causing delays and inefficiencies.

Development Takes Longer

The V Model emphasizes comprehensive testing. Each phase requires rigorous testing, which takes time, especially for larger projects. This produces high-quality software, but it may not be the most efficient method for deadline-driven applications.


The V Model requires dedicated testing teams to do rigorous testing throughout the development lifecycle. Smaller ventures with limited resources may require a large expenditure.  For smaller projects, a lighter process with less testing may work better.

The V Model's pros and cons should be considered in light of your project. So what is the right projects that can use the V Model? Let's come to the next part.

pron cons of v model
Pros and Cons of The V Model (Source: Internet)

When to Use the V Model?

The structured approach and focus on thorough testing of the V Model make it a useful method for certain kinds of projects. When the V Model shines, these things happen:

Clear Requirements

Stability is very important for the V Model. If the needs of the project are clear and won't change much during the creation process, the V Model works very well. Its clear steps and organized testing make sure that all of the software's parts are checked carefully against the set requirements.  This gives a lot of faith that the final product will live up to the original idea and meet the needs of users.

High-Risk Projects

The V Model's focus on early verification and validation is especially useful for mission-critical projects where failure could have very bad results. The thorough testing steps used throughout the development cycle help find and fix possible problems early on, which lowers the chance that major bugs will get to later stages.  This proactive method makes sure that the software is reliable and works as it should, even when things go wrong.

Projects with Regulatory Compliance Needs

In some fields, software developers have to follow strict rules. The V Model's focus on thorough paperwork throughout the whole process is a big plus. As proof that regulatory standards are being met, it is important to keep clear records of requirements, system design, and testing methods.  This can be very important during checks or certifications, making the process go more quickly and lowering the risk of problems with not following the rules.

v model vs waterfall model
Comparisons Between V Model And Waterfall SDLC Model (Source: Internet)

Comparisons Between V Model And Waterfall SDLC Model

The V Model and the Waterfall Model are both older SDLC methods that are known for their organized way of doing things. But there are some important differences between them that you should think about when picking the right method for your job. What they have in common and what makes them different are listed below.


  • Sequential Technique: Both methods use a step-by-step, sequential technique. Each stage of development happens in a straight line before going on to the next one.

  • Defined Planning: Both models promote planning and gathering requirements up front, which makes for a clear project roadmap.

  • Focus on Documentation: During the whole creation process, both methods stress how important it is to keep detailed documentation.


  • Testing Divergence: The V Model tests during development to find and fix issues. This produces high-quality software through early and continual testing. In contrast, Waterfall defers testing until later development. This technique may disclose major difficulties later in the project, requiring rework and delaying completion.

  • Flexibility: The V Model's structure can constrain projects with changing needs. Frequent modifications may require retesting and revisiting prior steps, causing delays and inefficiencies. The waterfall model is considerably less adaptable. Disruptive changes throughout development may require reworking earlier phases and delay or increase costs.

  • Time and Resources: The V Model takes longer than Waterfall because it emphasizes thorough testing. The V Model requires dedicated testing teams to undertake extensive testing, which increases resource needs. This speed advantage might lead to serious complications later on, requiring rework and undoing any early time savings.

  • Selecting the Right Tool: Mission-critical projects with well-defined requirements and excellent quality assurance benefit from the V Model. For projects with definite deadlines and predictable requirements that require forward preparation, the Waterfall methodology may work.

The differences between the V Model and the Waterfall Model can be illustrated below:


V Model

Waterfall Model

Testing Emphasis

Early and continuous testing throughout the development lifecycle

Testing primarily occurs at the later stages


Less flexible, struggles with evolving requirements

Even less flexible, significant changes require revisiting earlier phases

Development Time

Can take longer due to comprehensive testing

Generally faster due to less focus on testing in early phases.

Resource Intensity

Requires dedicated testing teams for thorough testing

Resource requirements may be lower


Ideal for projects with well-defined requirements and high-risk projects.

Best suited for projects with stable requirements and clear deadlines.

Best Practices for Implementing the V Model

The V Model provides a foundation, but it must be customized for your project to succeed. Consider these ideal practices:

Tailoring the V Model

The V Model is customizable. The rigidity can hamper its efficiency. The V Model must be customized for your purpose. If your project has changing requirements, include flexibility in the development process. This may involve accepting modest changes to prior phases without delaying the project.  The V Model can guide, but it needs customization to work.

Effective Communication

The V Model relies on clear communication and collaboration between development, testing, and stakeholder teams. Regular communication ensures everyone understands project requirements, testing goals, and challenges.  Developers must understand testing criteria, and testers must understand system functionality.  Progress and difficulties must be communicated to stakeholders. This collaborative setting encourages comprehensive development and testing, resulting in a better product.

Using Tools and Automation

The V Model's rigorous testing requires resources. Consider automation testing tools to streamline and boost efficiency. Automation lets testing teams focus on more complicated scenarios and exploratory testing. Version control systems also track changes and assist regression testing to prevent unintentional regressions in previously tested capabilities.  These technologies and automation methods help teams optimize the V Model process and produce better results with fewer resources.

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In conclusion, the V Model allows for simultaneous verification and validation at any level. It is ideal for projects with definite and predefined criteria. However, it is not appropriate for complex, large-scale projects with uncertain requirements. Therefore, when choosing the right model for your project, remember to consider the project's project criticality, the technology used, tools and techniques, etc.

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