Why Testing is needed?

Testing is necessary because the existence of faults in any product is inevitable.
Testing improves the reliability of the product.Imagine you are driving a car whose bracks are never been tested.Would you feel safe in driving that car?

Testing helps to deliver quality products that satisfy user’s requirements, needs and expectations. If done poorly,defects are found during operation,it results in high maintenance cost and user dissatisfaction,It may also cause failure.

Raising the reliability of the product means finding and removing errors. Hence one should not test a product to show that it works; rather, one should start with the assumption that the program contains errors and then test the program to find as many of the errors as possible.