Postconditions are specific conditions or states that must be true after a particular operation or process has been completed. They serve as a way to verify that the desired outcomes have been achieved and that the system behaves as expected. In programming, postconditions help ensure that functions or methods produce the correct results and maintain the integrity of the data. In the context of software development, postconditions are often documented alongside preconditions, which outline the requirements that must be met before an operation begins. By clearly defining both preconditions and postconditions, developers can create more reliable and maintainable code, ultimately leading to better software quality and user satisfaction.