What is Functional Testing?

My definition of Functional Testing

Functional Testing involves testing the functionality of a website or app, to ensure it works as expected, producing the expected results, in an effective way. Where relevant, Test Cases are used to test the functionality behaves as expected – with a specific set of inputs, the functionality is tested and the actual results compared against the expected results.

Wikipedia definition of Functional Testing

Functional testing is a quality assurance (QA) process and a type of black box testing that bases its test cases on the specifications of the software component under test. Functions are tested by feeding them input and examining the output, and internal program structure is rarely considered (not like in white-box testing). Functional testing usually describes what the system does. Functional testing differs from system testing in that functional testing “verifies a program by checking it against … design document(s) or specification(s)”, while system testing “validate