I dont know exact answer but,

Yes. In descriptive programing, we dont use object 
repository. we give proprties of the object in order to 
recognise it uniquely, in script.

Plz correct me if i'm wrong

Yes Naresh.. Ur absolutly correct..
U can use Descriptive Programming where object Repositary is
not necessary..

without repository the objects cannot be recognonised

because while we running the script,objects should be there 
in the object repository

please clear my doubt what is meant by "Descriptive 
Programming"?

Descriptive programming is doing programming giving 
description for an object in terms of value of the 
properties of the object and recognising the object during 
runtime without storing the object and its properties in 
object repository.
For example:
If you want to identify the winedit object with the value 
100 and ie editable in it we can write descriptive 
programming for this in the below given manner:
Set objdesc=Description.Create()
    objdesc("Class Name").value="winedit"
    objdesc("text").value= "100"
    objdesc("Enabled").value=True
Window("XYZ").Winedit(objdesc).Set "123"

yes, descriptive programming is the best way for 
recognizing the objects uniquely.

Maha Lakshmi, you are wrong we can recognise objects using 
descriptive programming as suggested by naresh and megha or 
the other way round is we can specify the properties in the 
statements itself like

Browser("name:=Google").Page("title:=GoogleHome").Link
("name:=Search").Click

You can see about Descrition.Create() in QTP help.

Yes Mahalakshmi what bhara provided is also correct. Now we 
are following the same for descriptive programming .
By 
Kamal (EDS Company)