Which type of testing focuses on the system's performance and scalability?

Performance Testing is focused specifically on measuring the system's performance under various conditions, including its responsiveness, speed, scalability, and stability under load. This type of testing is crucial for understanding how a system behaves when subjected to both typical and extreme workloads, ensuring that it can handle user demands effectively without degradation in performance.

In performance testing, key metrics such as response time, throughput, and resource utilization are monitored to assess the system's capacity to scale as the number of concurrent users or transactions increases. This helps in identifying bottlenecks or weaknesses that may affect user experience and system reliability.

Unit Testing, on the other hand, focuses on individual components or functions of the software to ensure they operate correctly in isolation. Integration Testing checks the interfaces and interaction between integrated components but does not primarily address performance aspects. Acceptance Testing verifies whether the system meets the business requirements and is ready for delivery but also does not concentrate on performance or scalability in the way performance testing does.