firt we have to create the scrpit aftr that just execute it 
and in executing time QTP take help of to find the object 
in appplication by using "object repository"

To find the unique ness in the objects qtp fallow the below 
process
1:It depends on Mandatory Properties
2: It depends on Assistve Properties
3:Smart identification
4:Ordinal identifiers

If smart identification is enable the order is 1,2,3,4
if smart identification is disable then order is 1,2,4

Mainly objectives are three type's OF PROPERTIES namely 
1) Mandatory properties,
2) Assistive properties
3)  ordinal identifier
firstly QTP traying to identifies mandatory  properties if 
it is not unique then identifies assertive properties if it 
is not unique then go to identifies ordinal identifier.

The object identification concept is based on four types of
properties and ordinal identifier. The four types of
properties are as follows:
1.Mandatory Properties(MP).  2. Assistive Properties(AP)
3.Base Filter Properties(BFP) and 4. Optional Filter
Properties.(OFP).
The test engineer will specify the list of MP,List of
AP,List of BFP, the List of OFP & an ordinal identifier
depending upon his desire.
The options BFP & OFP are available in smart identification
and one has to select the check box of smart identification
to list desired BFP & OFP. However, the information of BFP &
 OFP will hidden and QTP has its own method of how to use
these BFP & OFP of the particular object.
When all the four types are used, then QTP  will learn all
the properties of MP, BFP & OFP simultaneousely and thinks
whether it can identify the desired object or not. If QTP
feels that it can identify the object with MP,BFP & OFP then
it stops learning. Otherwise, it will learn the first
assistive property(AP) and then thinks again whether it can
identify the desired object or not. Now the QTP thinks again
whether it can identify the object. If it feels that it can
identify the desired object then it stops learnig. Otherwise
, it learns the second assistive property and the process
continues untill all the assistive properties were usedup.
If still the QTP feels that it cannot identify the object
then it learn the ordinal identifier and stops learning.

the above answers are correct..here some more information..

if u explain this definitely interviewer will ask u
.....what is Ordinal Identifier?

In Ordinal Identifier we have 3 properties..Index, Location
and Creation Time. we can select only one property for one
Object and Creation Time is only for Browser.

Index is Tab Order of a Object in Application.
Location is x,y position of a Object in in Application.
Creation Time is browser opened time.

If any queries...
nanda.dreddy@gmail.com