What is test execution?

Test execution is fundamentally about the active process of running tests against a software application to assess its functionalities and identify defects. This phase occurs after test planning and design, where the tests that have been previously defined are actually carried out on the system. During test execution, testers interact with the application, input data, observe its behavior, and document the outcomes, which include both the pass and fail results of the tests executed.

The importance of test execution lies in its role in validating that the software meets the specified requirements and behaves as expected in the real-world scenario. It is an essential step in the testing life cycle, as it directly contributes to understanding the quality and reliability of the software application.

In contrast, the other options pertain to earlier phases of the testing process such as planning, environment setup, and case design which are crucial but not considered as the execution phase itself.