Software performance testing ensures application reliability by evaluating how well an application operates under varying conditions and loads. This process helps identify bottlenecks, scalability issues, and potential points of failure before deployment. By simulating real-user scenarios, developers can assess not only load handling but also response times and resource consumption. Performance testing can take various forms, including load testing, stress testing, and endurance testing, each targeting specific application behaviors. Addressing the issues uncovered during testing leads to more stable and efficient applications, which is key to achieving user satisfaction and maintaining business operations effectively.