Driver script is the main Action, which will call all the 
unit scripts in a test.

Driver is a virtual environment, when one of the main 
module is not completed at the time of Integration Testing, 
then testing team installs a virtual environment called 
Driver and follows the bottom-up approach to test.

driver is actualy a piece of software which has the
capability to produce an input to invoke the proceeding
module...
drivers are used during bottom up integration testing and
are difficult to creat... (it can also be count as one of
the disadvantage of bottom-up testing)

correct me if m wrong...

Rajiv Kumar Jindal
(Test Engineer,Noida)

when you want a testing an application you create a driver 
in asp application with one case it develop in .net format. 
so when u sent a xml request to the asp application it will 
give result while in transformation driver is useful to 
carry your proper data from that application.

Driver a duplicate module fixed if any module in b/t is not 
ready..

While intigrating the modules in bottom/top approach if any 
mandatory module is not ready then they will be intigrate 
with temp program. This program is known as driver.

While intigrating the modules in top/down approach if any 
mandatory module is not ready then they will be intigrate 
with temp program. This program is known as stub.