we have our won model
v means verificaton& validation at the same time
verification conducted dovelopers and validation conducted 
testers in v model output give very quality product because 
testmanagement people involved in teting.
dis : it is very costly model,time consumeing
adv: very quality 

water fall model is is also used 
spiral model is very time consuming process and customer is 
give the continious requirment the we go to sprial model

     this is sreenivas from delhi
          contact no 9971747710
ok na bye bye bye....

In water fall model what we do is 
1)req.analysis
2)design 
3)coding
then (4) testing
5)implementation
means at the end of coding phase we go for testing,not 
before that.
but in V model that is varification and validation
we do 
1)req.analysis + testing (varification)
2)design + testing (varification)
3)coding +testing (validation)
4)testing (validation)
y? varification in req.analysis & design phase.Bcz in these 
two phases we cannot test a project in running conditions, 
bcz at this stage we have documents with us.
y? validation while coding and testing. Bcz in these phases 
we have our project in running condition, means we can 
execute a program using computer.so at these stages we can 
validate our project according to SRS.

Poonam, what are you trying to convey here?

With the asnwer given by you, it looks like you yourself 
confused, in future be clear for yourself first and then 
post your answer.