What are the different classes of testing and explain each of them?

 There are two widely divided classes of testing

a) Black box testing: Input/output driven testing is known as black box testing. This testing is specification focused where for every input given and expected output behavior of the application is validated. In layman’s language, we can say, testing which doesn’t involve code execution to validate the functionality of the application is known as Black box testing. Here the tester is more concerned about what the software does, rather than how it does.

b) White box testing: This type of testing is also known as structure-based testing. This validates how the software is implemented or let’s say how it works.

In layman’s language, we can say that any testing which involves testers intrusion into the code of the application to validate the flow and functionality of the application is known as White box testing. Here testers are more concerned about how the software works rather than
what it does.