... to geckodriver. Generally speaking, Selenium 3 enabled geckodriver as the default WebDriver implementation for Firefox. With the release of Firefox 47, FirefoxDriver had to be discontinued for its lack of support for the new multi-processing architecture in Gecko. Since geckodriver is a separate HTTP server that is a complete remote end implementation of WebDriver, it is possible to avoid using the Selenium remote server if you have no requirements to distribute processes across a matrix of systems.