Selenium is a popular open-source web based automation tool.WebDriver is one of the most powerful and popular tools of Selenium toolkit. WebDriver comes as an extended version of Selenium RC with superfluous advantages and addresses many of its limitations. WebDriver extends its support to many latest browsers and platforms, unlike Selenium IDE. WebDriver also doesnâ€™t require Selenium server to be started prior to execution of the test scripts, unlike Selenium RC. Selenium RC in aggregation with WebDriver API is known as Selenium 2.0. Selenium was so developed in order to support dynamic web pages and Ajax calls. It also supports various drivers to exercise web-based mobile testing.