Is it necessary to launch the browser's graphical interface when running tests with Selenium?

No, it is not necessary to launch the graphical browser interface when running tests with Selenium. You can use the so-called headless mode, where the browser operates without displaying a window. This speeds up test execution and saves resources, which is especially useful for CI/CD systems. For example, in Chrome, you can enable headless mode through options:

ChromeOptions options = new ChromeOptions();
options.addArguments("--headless");
WebDriver driver = new ChromeDriver(options);

Thus, tests will be executed without opening a visible browser window.