Program correctness refers to the degree to which a computer program behaves as intended. It ensures that the program meets its specifications and produces the expected outputs for given inputs. This concept is crucial in software development, as incorrect programs can lead to errors, crashes, or unintended behavior. To achieve program correctness, developers often use techniques such as formal verification, testing, and debugging. Formal verification involves mathematically proving that a program adheres to its specifications, while testing checks for errors through various input scenarios. Debugging helps identify and fix issues that arise during program execution.