What is "acceptance testing" used for?

Acceptance testing is a critical phase in the software development process where the completed system is evaluated to ensure it meets the specified requirements of the end users. This type of testing is typically performed by the end users or clients and is used to determine if the software behaves as expected in a real-world environment and fulfills the needs for which it was designed. The primary goal is to verify that the system delivers the functionality and performance that users anticipate, ensuring that any discrepancies are identified and resolved prior to the software's release.

The focus of acceptance testing is on validating user requirements rather than assessing the technical performance, compatibility, or security features of the system; hence the other options, while important in their own right, do not address the core purpose of acceptance testing.