5 differences and an example attached with each difference?

In today’s world of increasingly complex software systems, ensuring high quality is not just
desirable, it is essential. Two key activities that play a central role in achieving this goal are
Verification and Validation. These are not merely technical steps, but foundational pillars of software
quality assurance, ensuring that the software is both built correctly and built for the right purpose.
While often mentioned together, they serve very different roles: Verification checks whether the
system conforms to its specifications and design, while Validation ensures that the system meets the
actual needs and expectations of its users.

As emphasized by software engineering expert Ian Sommerville, these processes collectively aim to
deliver software that is not only functionally correct but also reliable, usable, and valuable in the real
world.

Definitions with Author Support

According to Ian Sommerville in Software Engineering (10th Edition), Verification and Validation
(V&V) are distinct yet related processes that help establish confidence in a system’s fitness for use

Verification: It answers the question “Are we building the product right?”. It ensures that the
software is being developed according to its design and specification. It mainly involves checking
and reviewing work products without executing the code

Validation: It answers “Are we building the right product?”. It ensures that the final software
product meets the actual needs of the user or customer. It involves testing and executing the software
in real or simulated environments

Differences Between Verification and Validation

1. Purpose ( Doing It Right vs. Doing the Right Thing )

Verification ensures that the software is being developed correctly according to the plan, design, and
rules. It's about checking that each step is performed properly.

Validation, on the other hand, ensures that the final product actually solves the user's problem. It's not
just about the process, but about the result.

Why this matters: A product can be built perfectly and still fail if it does not serve the user’s real
needs.

Example: In a school management system, the verification process confirms that all modules like
attendance, grading, and scheduling match the specifications. But during validation, staff realize they
cannot send notifications to parents, which is essential. So, the system is verified, but not validated
for actual school use.

2. Core Question ( "Right Product" vs. "Product is Right" )

Verification asks: “Are we building the product right?” , it’s a technical check.

Validation asks: “Are we building the right product?” , it’s a user-oriented check.

Why this matters: These two questions reflect two different views: one from the developer, the
other from the user. Both are valid, but they focus on different outcomes.

Example: A university website is verified to load quickly and pass accessibility tests. However,
when validated by students, many report they can’t easily find exam schedules or results, defeating
the purpose of the site. So, technically correct, but functionally lacking.

3. How They Are Performed ( Static vs. Dynamic )

Verification uses static methods such as code reviews, document checks, walkthroughs. No need to
run the software.

Validation involves running the software with real or test users such as functional testing, user
feedback, etc.

Why this matters: Verification catches mistakes early, while validation ensures the whole system
works as intended in real conditions.

Example: In a payroll software, verification confirms the salary calculation logic is coded correctly
based on the formulas. But in validation, when HR tests the software, it fails to calculate bonuses
correctly during leap years , a bug that only appears during runtime with real data.

4. When It Happens ( Early vs. Later )

Verification is done during the early phases , while planning, designing, or coding.

Validation happens after development , during testing, user trials, or acceptance checks.

Why this matters: Verification helps prevent problems, but only validation confirms the final
product is ready for real use.

Example: While developing a hospital patient record system, verification checks that the database
structure, security layers, and module flow follow requirements. But after full deployment, validation
reveals that doctors cannot print prescriptions directly, a major usability issue not caught earlier.

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5. Who Performs It ( Internal Team vs. Users )

Verification is done by the software team such as developers, QA, or testers.

Validation involves real users, clients, or end-users who judge the software based on their actual
experience.

Why this matters: Developers know how the system should work. Users know how it must work in
their real environment.

Example: In a mobile banking app, developers verify that the login system and OTP (one-time
password) functions as designed. But when real customers use it (validation), many report that OTPs
arrive too slowly on rural networks, making login frustrating and unusable in real-life conditions.

Additional Differences Between Verification and Validation

Aspect Verification Validation

Definition Ensures the software correctly Ensures the software is traceable

implements specific functions as per and aligned with customer
design. requirements.

Bug Detection Helps identify bugs early in the Finds bugs missed during
development process. verification, often at later stages.

Responsibility Performed by the QA team, focusing Performed by the testing team,

on reviewing documents and designs. executing the system in real or
simulated environments.

Human vs. Computer Done by humans through reading and Done by computers through actual
reviewing (manual inspection). execution and observation of results.

Lifecycle Stage Begins after the requirements are Begins as soon as the project starts,
documented and design is complete. often overlaps with development
activities.

Error Approach Aims at preventing errors before they Aims at detecting errors in the
occur. working software.

Alternate Terms Also called white-box testing or static Also called black-box testing or

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 testing. dynamic testing.

Defect Detection Rate Can uncover approximately 50–60% Can uncover around 20–30% of
of total defects. remaining defects after verification.

Stability Depends on reviewer’s judgment — Based on factual software behavior

may vary by person. — more objective and consistent.

Conclusion

In software engineering, Verification and Validation are not just technical processes, they represent
two distinct mindsets that together ensure true software quality.

Verification is about building the system right such as checking accuracy, structure, and conformance
to design. It focuses on the internal correctness of development activities.

Validation, on the other hand, is about building the right system such as ensuring the final product
delivers real value to its users. It focuses on the external effectiveness and relevance of the product.

Neglecting either one leads to failure: software that is either flawed or pointless. That’s why these
two must go hand in hand ,Verification ensures trust in the process, while Validation ensures trust in
the outcome.

Ultimately, software must not only be technically perfect, but also practically meaningful.
Understanding the actual difference between Verification and Validation helps avoid the critical
mistake of creating a system that works well but serves no real purpose — the most expensive kind
of failure in software.