virtual object is nothing but whenever winrunner cannot 
identify the non-standard objects then we go for virtual 
object wizard..and moreover when we record the non-std 
object it will treat it as window.where ever we click on 
the window.

virtual object is not a standard object. some time images 
in the application acts as objects. by clicking on them we 
can do some action. those are called virtual objects. in  
gui map file, the objects are stated as
    virtual:TRUE in addition to other properties of normal 
objects

By using this we convert non gui object in to standared gui 
object.suppose any image or bitmap win runner can be 
treated has a push button(standerad gui object)like that

Applications may contain bitmaps that look and behave like
GUI objects. WinRunner records operations on these bitmaps
using win_mouse_click statements. By defining a bitmap as a
virtual object, you can instruct WinRunner to treat it like
a GUI object such as a push button, when you record and run
tests.