Software Testing is an activity to check that the actual result matches with the expected result.
Software Testing is a Verification and Validation process to check that the application/product is working as expected, as per requirements.
Intention of Software Testing are :
Application/ Product is defect free
Find BUGS
Example : Calculator ---> Add Function = 5+4 -> 9
As shown above right answer is " 9 ", but when if calculator is giving answer " 10 "
Hence, the calculator is working but the answer is not as expected