what is selenium webdriver 
                     What is Selenium webdriver?
Selenium Webdriver is an open source collection of APIs used to test web applications. The 
Selenium Webdriver tool is used to automate testing of web applications to see if they work 
as expected.
It supports various languages like Java, PHP, Perl, Python, Ruby, C# and JavaScript.
It supports the browser like IE, Mozilla Firefox, Safari, Google Chrome and Opera.
It supports the operating systems like Windows, Linux, Mac and Solaris.
It is very flexible and easy to use as compared to other functional tools, because it 
supports multiple languages.
It is used to handle multiple frames, multiple browser windows, popups, and alerts.
It is also used for advanced user navigation such as drag-and-drop, mouse hover, etc.
LANGUAGES
Basic Steps in a Selenium WebDriver Script
Create a Selenium Webdriver Instance.
Navigate to the required webpage on which we want to perform the operation.
Use the Selenium locator to find the web element in your web page.
Perform the user action/actions on the web element.
Preload the expected output/browser response to the action.
Run the test.
Record the results and compare the results with the expected output.
Limitations of Selenium WebDriver
Support for new browsers is not immediately available as compared to Selenium RC.
There is no built-in command to automatically generate test results