For performance testing application should be tested by different users at same time on same /different networks to check its performance. Though this can be performed manually, it is very time taking, requires lot of resource so it is very expensive. By Creating Virtual users we can execute performance testing very easily. For example, if we are testing any web application. We have to check its performance by increasing the load on it. In one scenario if the client wants his site to b tested by viewing/ accessing the site by 1 lac users from different places all over the world on particular configuration of the system at the same time, by creating virtual users in loadrunner one can test this.