What are the differences between between functional & non-functional testing methodologies?

Can anyone please help me in diffrentiating between functional & non-functional testing methodologies…

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While there is not much difference between functional and non-functional testing from a user point of view, if you look at it as a tester, then you might find many differences between them. Below is a detailed comparison of functional and non-functional testing:


When it comes to the key difference between functional and non-functional testing, it is that functional testing is meant to check on the functionality aspect of the software or application. On the other hand, non-functional testing is meant to test on performance and usability aspects of the product under test.

User acceptance testing, regression testing, interoperability testing, globalization testing are a few examples of functional testing practices. On the other hand, non-functional testing involves scalability testing, reliability testing, volume testing, etc.


Functional testing verifies each function of the software application operates in conformance with the requirement specification. It involves black box testing and not concerned about the source code of the application. Every functionality of the system is tested by giving appropriate input, verifying the output and comparing the actual results with the expected results.

Non-functional testing is a type of testing to check non-functional aspects like performance, usability, reliability, etc. of a software application. It is designed to test the readiness of a system as per nonfunctional parameters which are never addressed by functional testing.

Functional describes what the product does whereas Non Functional describes how the product works.