Test Strategy is basically an approach of testing the 
functionality of application it is just like the road map 
of testing the project.

Test Strategy is a organisational level term, used for
testing the differenent projects in an organsiation.

The planning to cover the product so as to develop an 
adequate assessment of quality.
the purpose of the test strategy is to clarify the major 
tasks and challenges of the test peoject.

It ia an approach. In this stage they approach how a 
product is handled by QA and only by testing based on the 
test policy