Building and executing Selenium projects involves utilizing automation platforms to test websites more efficiently by transitioning from manual to automation testing, while still reserving exploratory testing for manual methods. Selenium, an open-source framework, facilitates cross-browser and cross-platform testing with components like Selenium IDE, Selenium WebDriver, and Selenium Grid, which help in writing, executing, and scaling test scripts across different environments. Integration with tools such as TestNG, JUnit, Maven, Gradle, and CI/CD solutions like Jenkins enhances test orchestration and management. The tutorial outlines setting up Selenium projects in Java using Maven or Gradle, demonstrating the execution of test cases through IntelliJ IDEA, and leveraging cloud-based Selenium Grids like LambdaTest for scalable testing. It highlights the importance of efficient project management and dependency handling using tools like Maven, while also offering guidance on writing and executing Selenium test cases with practical examples and code snippets.