What is the testing process?
Verifying that an input data produce the expected output.
What is the difference between testing and debugging?
Big difference is that debugging is conducted by a programmer and the programmer fixes the errors during debugging phase. Tester never fixes the errors, but rather find them and return to programmer.
What is the difference between structural and functional testing?
Structural is a "white box" testing and based on the algorithm or code. Functional testing is a "black box" (behavioral) testing where the tester verifies the functional specification.
What is a bug? What types of bugs do you know?
Bug is a error during execution of the program. There are two types of bugs: syntax and logical.
What is the difference between testing and quality assurance (QA)?
This question is surprisingly popular. However, the answer is quite simple. The goals of both are different: The goal of testing is to find the errors. The goal of QA is to prevent the errors in the program.
What kinds of testing do you know? What is it system testing? What is it integration testing? What is a unit testing? What is a regression testing?
You theoretical background and home work may shine in this question. System testing is a testing of the entire system as a whole. This is what user see and feels about the product you provide. Integration testing is the testing of integration of different modules of the system. Usually, the integration process is quite painful and this testing is the most serious one of all. Integration testing comes before system testing. Unit testing is a testing of a single unit (module) of within system. It's conducted before integration testing. Regression testing is a "backward check" testing. The idea to ensure that new functionality added to the system did not break old, checked, functionality of the system