Which type of testing focuses on the overall behavior and performance of the system?

System testing is a type of testing that evaluates the complete and integrated software system to ensure it meets specified requirements. This testing type focuses on the overall behavior and performance of the system as a whole. It is typically performed in a complete and fully integrated environment and involves the execution of various test cases that assess the software's functionalities, performance, usability, security, and more from an end-user perspective.

During system testing, testers aim to identify discrepancies between the actual and expected behavior of the system, validating not only individual components' functionality but also how they work together as a unified system. This scope makes system testing crucial for ensuring that the application performs well under different conditions and meets the user's needs and expectations prior to deployment.

In contrast, other types of testing like unit testing focus on individual components, integration testing looks specifically at the interfaces and interactions between those components, and acceptance testing evaluates the system from the user's perspective to determine if it is ready for release. Each of these types has its specific goals and focuses at different stages within the software development lifecycle, but system testing uniquely stands out as the phase that encompasses the entire system's overall performance and behavior.