We use Virtual User concepts in LoadRunner(LR). In LR we 
create Scripts for one user. Now we create as many VUsers 
as we want through LR. Once we create the VUsers, LR 
performs the actions with the number of VUsers we created 
and measures the performance.

Befor knowing What V users are we should think why to have 
V users and appreciate its function. While testing an 
application with 50 people simultaneously login the 
application, Its highly impossible that every one logs in 
at the same point of time. Thats y v use V users.Here V 
stands for Virtual....

As the word clarify it's meaning, these are the users 
created by script-functions in load runner in order to 
perform the load testing of the application. It is not 
possible to simultaneous login of the large numbers of 
users by a group of testers at the time of testing and we 
have to check the load for 100 or 1000 or more users(which 
is the actual scenario). So, in this case the VIRTUAL USER 
concept is used.

virtual user is a simulation of real user. it is generated 
by virtual user generator, a component in LR. using load 
runner we can create min of 9999 vusers

Load runner replaces human users with yirtual users or 
vusers.
Purpose:
(1) with increasing the number of vusers we increase the 
load oon the system
(2)Example: we can observe how a server behaves when 
hundered of Vusers simultaneously withdraw cash from the 
bank

loadRunner replace the human user with Vuser

In load runner we create a script for one user and create 
no of vusers.To replace human users we create vusers.
If a web application is used by 1000 people at a time and 
we have to test the application then we cannt bring 1000 
testers to test the app.Instead of that we use the concept 
of vusers.

Correct me if i am wrong