Correctness is the most basic quality goal. It means that, when valid inputs are given and the system is in a valid state and under reasonable load, the system's behavior and results will be correct.
Functionality > Robustness
Robustness is the system's ability to gracefully handle invalid inputs. It should never be possible for any user input to crash the system or corrupt data, even if that user input is abnormal, unexpected, or malicious.
