GeckoDriver

What is GeckoDriver?

GeckoDriver is the driver executable that lets WebDriver communicate with Mozilla Firefox, implementing the W3C WebDriver protocol between the test script and the browser.

Setting It Up

System.setProperty("webdriver.gecko.driver", "path/to/geckodriver");
WebDriver driver = new FirefoxDriver();

Why It's Needed

Since Firefox 48, Mozilla requires WebDriver-compatible clients to use GeckoDriver rather than communicating directly with the browser, replacing the older built-in FirefoxDriver approach.