V model is one of the software development model where 
testing is done parallely with the application development.
i.e When the development of application is in process test 
engg will test each and every out come document

for example:Consider a bank application consisting of three 
modules admin,banker and the customer.
The development team has completed the admin module and 
working with banker module.At this stage the testing team 
will test the admin module while the developers are in 
process with the banker module ie before completing the 
who;e application.This is the process of v-model.There can 
be changes in the application with v-model.


Waterfall model is used when requirement are clear and 
complete and for the small projects.Here we cant 
incorporate new changes in the application

V Model can be viewed as a process improvement technique or 
model as well. Using this model /technique we can improve 
the Testing Process by that way we can reduce time of 
Testing which results in the Reduction of the Testing 
Budjet.

Also, we can find more critical bugs in each stage which 
can be resolved at that time itself reducing effort and 
imnimizing the number of faults found during Dynamic 
Testing.

So, it can be Used as Model to Improve Testing Quality and 
a Technique to improve Product Quality.

V Model is the process model to provide quality product by 
combining SDLC and STLC. In this model Both SDLC & STLC 
works parallely. Left Hand side of the V model contains 
SDLC in downhill direction whereas right hand side of the V 
model contains STLC in Uphill direction.