Load Runner is a performance and load testing product for examining system behaviour and performance, while generating actual load. Load Runner can emulate hundreds or thousands of concurrent users to put the application through the rigors of real-life user loads, while collecting information from key infrastructure components (Web servers, database servers etc). The results can then be analyzed in detail, to explore the reasons for particular behaviour.
So, given an application and a computer system with Load Runner, one can simulate a large number of users accessing the server simultaneously. Once activities have been defined, they are repeatable. After debugging a problem in the application, managers can check whether the problem persists by reproducing the same situation, with the same type of user interaction.
Working in Load Runner involves using three different tools which are part of Load Runner. They are Virtual User Generator (VuGen), Controller and Analysis.