The two legs
The left side of the “V” describes the system from coarse to fine: requirements → architecture → detailed design → implementation. The right side tests from fine to coarse: unit test → integration test → system test → acceptance. Each level on the left has its counterpart on the right.
Verification and validation
Verification checks whether the system was built correctly (against the specification). Validation checks whether the right system was built (against the actual need). Both are an inseparable part of the V-model.
Why it pays off
Errors are found early and at the right level, and tests are documented in a traceable way — a prerequisite for safety-critical systems and standards such as ASPICE or ISO 26262.
Frequently asked questions
Isn't the V-model inflexible?
It describes the link between specification and testing — not necessarily a rigid waterfall. We combine the V-model logic with agile methods (Scrum) to stay adaptable.
Do I need it for my project?
For safety- or approval-relevant systems (automotive/railway/medical), practically always. We scale the effort to match your project's risk.