Descritive Programming is develoed based on VbScript

Descriptive prog. execution is mainly based on Object 
Properties  description

when u want to write DP then first u go for 
description.create()Object with assigning of object 
properties

generally we can identify object properties with the help 
of OBJECT SPY


for Example we want to prepare DP for Login operation
Step1 : Prepare Object Descripton

Step 2: Write VbScript for that Login Operation(with help 
of DP)
SystemUtil.Run "Path of Server","",Path of .exe".Open
Step 1
Set Login_Obj = Description.Create()
Login_Obj ("name").Value = "Login"
Login_Obj ("micclass").Value = "Dialog"

Set Uname_obj = Description.Create()
Uname_obj ("name").value = "username"
Uname_obj ("micclass").Value = "WinEdit"


Set Pword_obj = Description.Create()
Pword_obj ("name").value = "username"
Pword_obj ("micclass").Value = "WinEdit"

Set Ok_obj = Description.Create()
Ok_obj("name").value = "OK"
Ok_obj("micclass").value = "WinButton"


Step2
Dailog(Login_obj).Activate
Dailog(Login_obj).WinEdit(Uname_obj).Set "xxxx"
Dailog(Login_obj).WinEdit(Pword_obj).SetSecure "xxxx"
Dailog(Login_obj).WinButton(Ok_obj).Click

Make QTP to run an application through Script.

The Script may contain .VBS functions,JS files,XML Files.

Describing an object with in an application without 
recording the properties of that object is 
called "Descriptive Programming"

Instructing QTP to perform Operations on AUT objects which 
are not present in Object repository.

Whenever QTP records any action on any object of an 
application ,it adds some description on how to recognize 
that object to a repository of objects, which is known as OR
(Object Repository)

Descriptive Programing is nothing but but describing the 
object properties in the script itself. We do not need 
object reposiroty for descripting programing. and one more 
thing is that we cann't use check points in descriptive 
programing, since we will not use object repository in DP.

Descriptive programing is nothing but without using the 
objectRepositary we are writing the script for the 
functionality.
 Suppose we have a web application that has not been 
developed yet.Now QTP for recording the script and adding 
the objects to repository needs the application to be up, 
that would mean waiting for the application to be deployed 
before we can start of with making QTP scripts. But if we 
know the descriptions of the objects that will be created 
then we can still start off with the script writing for 
testing.