With selenium web driver you can write very powerful test scenarios
for your web application. The idea is that all applications need at some
point a kind of integration testing where you can see the application in
action on your screen. In the end, the whole goal of your development
effort is the web application running in your browser (if you are
developing a web application, of course). With the Selenium webdriver you
can control the browser interaction, like clicking on links and filling in
fields, from within the java code itself, there is no need any more for the
javascript scripts of selenium RC.
Beside the fact you need to know that your application works as
specified in the requirements, it is also important to know it will run in
more than one browser. This text explains how you can easily run the same
test in different browsers.