During which testing phase is the software tested by real users for functionality and usability?

The testing phase where software is evaluated by real users for functionality and usability is beta testing. During this stage, the software is released to a select group of external users outside of the development team. These users interact with the software in a real-world environment, allowing them to provide feedback on how well the software meets their needs and expectations.

This phase is crucial because it helps identify issues that might not have been uncovered during earlier testing stages, such as unit testing, which focuses on individual components of the software, and system testing, which assesses the overall functionality of the complete system against requirements. Alpha testing, on the other hand, is typically conducted within the development organization, not involving end-users. In contrast, beta testing incorporates real user feedback, making it a vital step for validating both functionality and usability before the official release.