Verification and validation play a crucial role in the development of high-quality software, ensuring that a product meets all customer and stakeholder requirements. Software testing can be described as the process of examining a system's functionality and behavior through verification and validation activities. Many people, including professionals, often confuse verification and validation, and some even use these terms interchangeably. This confusion typically arises from a lack of understanding about the distinct purposes and objectives that verification and validation address.
Verification
Verification testing is the process of ensuring that the software is designed and developed according to specified requirements. Simply put, we check whether we are building the product correctly — whether our software aligns with the customer's requirements.
Verification is an ongoing process that begins long before formal testing and continues until the software application has been reviewed and released. This process involves examining specifications, architecture, and code created during the software development stages.
After verification comes validation.
Validation
Validation is the process of checking whether the software meets the client’s real needs and expectations. Validation typically occurs after the entire software development process is complete, assessing whether the client received the product they anticipated. Unlike verification, validation focuses solely on the final product, disregarding internal processes and technical details of the development stages.
Validation is a one-time process that begins only after verification is complete. It can involve all forms of testing related to the final product, including both white-box and black-box testing.
American software engineer and distinguished computer science professor Barry Boehm described verification and validation as follows:
Verification: are we building the product right?
Validation: are we building the right product?
Verification vs validation: key differences
The main difference between verification and validation is that verification assesses the product for compliance with the specific requirements of each development stage, while validation evaluates the final product for its alignment with end-user needs.
The goal of verification is to examine the application’s architecture and specifications, whereas the objective of validation is to confirm the actual product.
| Aspect | Verification | Validation |
|---|---|---|
| Definition | Ensures the product meets specified requirements and is built correctly at each development stage | Confirms that the final product meets end-user needs and intended use |
| Primary focus | Product architecture, design specifications, and code quality | User requirements, functionality, and usability |
| Goal | To identify issues early by checking that requirements are correctly implemented | To ensure the product works as expected and fulfills user requirements before release |
| Type of testing | Static testing methods, including inspections, walkthroughs, and reviews | Dynamic testing methods, such as functional, system, and user acceptance testing |
| Responsibility | Generally performed by developers, designers, and QA teams during the development phase | Primarily involves QA teams, testing teams, and sometimes end-users |
| Execution stage | Conducted throughout the development cycle, often before code execution | Performed after development, during or after system integration, and often just before deployment |
| Approach | Answers “Are we building the product right?” focusing on adherence to specifications | Answers “Are we building the right product?” ensuring functionality and usability |
| Outcome | Identifies design flaws, requirement gaps, and deviations from standards early | Identifies functional and usability issues, enhancing the quality and reliability of the product |
Examples of verification vs. validation
Let’s see what verification and validation might look like for a rideshare app.
Verification
At the verification stage, we review requirements and design specifications to ensure that the rideshare app’s design, architecture, and documentation meet the initial business and technical requirements.
The development team and stakeholders review the app’s design document, which includes specifications for booking rides, payment processing, GPS tracking, and user communication (e.g., driver-passenger chat). During this review, they check that all planned features align with the functional requirements, such as requesting a ride, estimating fare, selecting a payment method, and receiving a notification when the ride arrives.
This activity ensures the team builds the app correctly according to agreed-upon specifications before any development begins. They’re not testing the app yet; they’re confirming that the planned functionality matches the design requirements.
Validation
During the validation process, we conduct beta testing with real users to ensure the app meets user needs and performs as expected in real-world conditions. After development, the ride-sharing app is released as a beta version to a select group of users. Testers use it in real-world situations to book rides, pay through the app, communicate with drivers, and rate the service. Users provide feedback on the app’s usability, functionality, and performance, such as how quickly a ride is found, if the GPS accurately shows the driver’s location, and if the payment processing is seamless.
This activity focuses on whether the app, as built, actually meets user expectations and real-world requirements. It ensures the final product functions well for end-users, addressing usability and performance rather than just alignment with the initial design.
Verification and validation are both essential components of testing
Software testing is incomplete until it undergoes both verification and validation. Verification and validation are essential components of the software testing workflow, as they ensure that the final product meets project requirements, reduce the likelihood of defects and product failure, and guarantee that the product meets quality standards and the expectations of all stakeholders.
