Test cases are fundamental components of the software testing process, serving as a detailed description of how a particular feature or functionality of a software application should be tested. Each test case typically includes a unique identifier, a description of the test scenario, preconditions, input data, expected results, and postconditions. The purpose of test cases is to verify that the software meets its specified requirements and functions correctly under various conditions. They can be categorized into different types, such as functional test cases (focused on specific functionalities), non-functional test cases (addressing performance, security, and usability), and edge cases (testing the limits of input values). Well-designed test cases help identify defects early in the development process, improve software quality, and facilitate regression testing after changes or updates. Additionally, they serve as documentation for future testing efforts, ensuring consistency and traceability throughout the software development lifecycle.