When LoadRunner is used?

as we all know that functionality testing helps ensuring that the product/application works fine according to the requirments and the client verifications are validated. This is always done by single user and depending upon the complexity of the application or the product, many test cases are written to ensure that the components functions as intended, but when the application passes this TollGate of functional testing, there is always question of what will happen to the application/product when multiple users are accessing them. Here comes the load testing which ensures that the application performs without breakdown for the required users as indicated in the CS ( customer specificatio ) document. For this we need to ensure proper loadtesting is done using automation as we all know we cannot ask 50 real users sitting b4 a computer and click is done, moreover all the areas of concerned will not be covered. One such loadtesting automated tool is loadrunner which is used to emulate the behaviour of real time user. Here the loadrunner is used, there are other load testing tools in the market but Mercury stand in forefront.