IBM Rational Performance Tester is a tool for creating, running, and analyzing performance tests to validate the scalability and reliability of web and enterprise applications before deployment. It allows users to quickly create performance tests without coding by recording user interactions. It also automates the identification and management of dynamic server responses and integrates server resource monitoring to help identify potential performance bottlenecks. The tool supports data-driven testing and realistic workload modeling to simulate real-world user loads. It assesses performance against service level agreements and provides reporting to determine if applications meet scalability and performance objectives.