Selenium Webdriver is a widely used tool for the automated testing of web applications. It has become popular because you can control and interact with an application the same way a user would with an actual web browser. Selenium can automate every action a user would take in a browser on multiple operating systems and using multiple browsers, including Chrome, Firefox, Edge, Internet Explorer, and Safari. This means it can be used to test that some functionality works the same in all supported browsers. Webdriver is how you interact with Selenium. It is a simple programming interface that you interact with by writing code and calling its API. Scripts to run Selenium Webdriver can be written in Java, JavaScript, C#, and Python. You can even take screenshots during the testing process to determine the state of the page during the test.