What is the role of design by contract in Object-Oriented Programming, and how does it enhance software reliability and correctness?

Design by contract (DbC) is a software development approach where classes explicitly specify their preconditions, postconditions, and invariants. DbC helps clarify the expected behavior of classes and establishes a mutual agreement between the client and the supplier of a class. By adhering to these contracts, developers can detect and prevent errors early in the development process, leading to more reliable and correct software.