QUnit is a powerful, easy-to-use JavaScript unit testing framework. It's used by the jQuery, jQuery UI, and jQuery Mobile projects, among others. QUnit facilitates writing and running tests in any JavaScript environment, allowing developers to ensure code quality and detect regressions early. It promotes readable test suites, offering assertion methods for various data types and built-in reporting. Simple HTML integration and a clear API make it suitable for both beginners and experienced testers.