The article provides a comprehensive guide on setting test case priority in TestNG, an open-source test automation framework commonly used with Selenium. It explains how the Priority attribute in TestNG is used to define the execution order of test cases, allowing testers to specify which tests should run first. The default priority is zero, but users can assign both positive and negative priorities to influence execution sequence. The guide also describes scenarios when tests have the same priority, resulting in alphabetical execution, and highlights issues that may arise when tests with identical priorities are run in parallel. The article further demonstrates implementation through various examples and scenarios, including prioritized, non-prioritized, and mixed-method priorities, while also touching on the integration of LambdaTest for cross-browser testing. It underscores the importance of understanding priority settings to effectively manage test execution order, ensuring the reliability of automated testing processes.